Wow, Here's New One For Me - the joy of touring old guitars.

[Offshore Angler]

So last show I was using my 40 year-old Sheraton ( not a Lester, but this would still apply) and during the second set I noticed the neck tone pot was getting really stiff.

No biggy, handed to my Tech and asked him to check it out, He agreed the pot was binding badly but he hasn't worked on semi-hollows too much. Since he has shown interest and aptitude in getting into repairs I told him "Let's check it out together." I mean, it's a pot, a very simple part to change. I showed him how to remove old, brittle knobs and explained that's the biggest pitfall of working on older guitars. I pull the pot out and before I unsolder it I tried to turn it by hand and its' locked up tight. Weird. Not how they usually fail. Out of curiosity ( and knowing no matter what I was going to replace it anyway) I hit the shaft with a shot of WD40. All of a sudden the pot broke free. Gee, that's cool. never saw that happen before. I'm like "What the heck is up with this thing?"

Took a few minutes but I figured it out - you're gonna like this one. Turns out the outer threaded sleeve of the pot had cracked around it's circumference at the minor axis the thread. This created a condition where the clamping force of the nut caused the two parts to move slightly off the axis of the shaft with respect to each other, locking the shaft.

Interestingly, I pulled the other tone pot and found it partially cracked as well.

I get it, changing a pot isn't exactly rocket surgery but I found the failure mode fascinating. These appeared to be corrosion stress cracks. The pots had 40 years of crusty goodness on them.

Anyone else ever seen that happen?

 

[GreenBurst]

Had not seen this in the past 45 years. I have electric guitars that are 63 years old to 4 years old.

If it did happen I sure hope it's not the lone 335 I own.

 

[zacknorton]

digg it... except for the wd40 part..... never spray that on pots. it's a MAGNET for debris.

 

[Offshore Angler]

Here's a pic of the little bastard.

WD40 was used only because I knew the part was coming out and wanted to sus the issue. Unless it's a rare vintage original, whenever a pot comes out of an old 335-style it never goes back in, it gets replaced. Too much hassle not to. I would use naptha for just cleaning. De-Oxit is good for temporary or trying to save a valuable date coded pot, but is usually temporary at best.

 

[corpse]

So last show I was using my 40 year-old Sheraton ( not a Lester, but this would still apply) and during the second set I noticed the neck tone pot was getting really stiff.

No biggy, handed to my Tech and asked him to check it out, He agreed the pot was binding badly but he hasn't worked on semi-hollows too much. Since he has shown interest and aptitude in getting into repairs I told him "Let's check it out together." I mean, it's a pot, a very simple part to change. I showed him how to remove old, brittle knobs and explained that's the biggest pitfall of working on older guitars. I pull the pot out and before I unsolder it I tried to turn it by hand and its' locked up tight. Weird. Not how they usually fail. Out of curiosity ( and knowing no matter what I was going to replace it anyway) I hit the shaft with a shot of WD40. All of a sudden the pot broke free. Gee, that's cool. never saw that happen before. I'm like "What the heck is up with this thing?"

Took a few minutes but I figured it out - you're gonna like this one. Turns out the outer threaded sleeve of the pot had cracked around it's circumference at the minor axis the thread. This created a condition where the clamping force of the nut caused the two parts to move slightly off the axis of the shaft with respect to each other, locking the shaft.

Interestingly, I pulled the other tone pot and found it partially cracked as well.

I get it, changing a pot isn't exactly rocket surgery but I found the failure mode fascinating. These appeared to be corrosion stress cracks. The pots had 40 years of crusty goodness on them.

Anyone else ever seen that happen?

I had the same thing happen with the volume pot in a 63 Fender Deluxe- it just seized. Andrew @ Andrews never gave me the autopsy results- he was more “ it doesn’t work si fix it”.
Scary for someone that does it for a living.

 

[charliechitlins]

That sleeve is quite thin, I suspect over-tightening by someone who wanted to keep the pots from spinning but couldn't be bothered with installing a star washer inside.
I, too, have seen a lot of old pots, but never that.
That's often pretty cheap metal (pot metal? Har!) and there can be a lot of variance in those alloys.
Maybe a bad batch of metal, but my money would be on it being gorilla-ed.

 

[oxyen33d]

So last show I was using my 40 year-old Sheraton ( not a Lester, but this would still apply) and during the second set I noticed the neck tone pot was getting really stiff.

No biggy, handed to my Tech and asked him to check it out, He agreed the pot was binding badly but he hasn't worked on semi-hollows too much. Since he has shown interest and aptitude in getting into repairs I told him "Let's check it out together." I mean, it's a pot, a very simple part to change. I showed him how to remove old, brittle knobs and explained that's the biggest pitfall of working on older guitars. I pull the pot out and before I unsolder it I tried to turn it by hand and its' locked up tight. Weird. Not how they usually fail. Out of curiosity ( and knowing no matter what I was going to replace it anyway) I hit the shaft with a shot of WD40. All of a sudden the pot broke free. Gee, that's cool. never saw that happen before. I'm like "What the heck is up with this thing?"

Took a few minutes but I figured it out - you're gonna like this one. Turns out the outer threaded sleeve of the pot had cracked around it's circumference at the minor axis the thread. This created a condition where the clamping force of the nut caused the two parts to move slightly off the axis of the shaft with respect to each other, locking the shaft.

Interestingly, I pulled the other tone pot and found it partially cracked as well.

I get it, changing a pot isn't exactly rocket surgery but I found the failure mode fascinating. These appeared to be corrosion stress cracks. The pots had 40 years of crusty goodness on them.

Anyone else ever seen that happen?

WD40 fixing the pot for five seconds before revealing the whole thing was literally cracked is the most old guitar repair story ever honestly kinda impressive it survived gigs that long before fully dying.