[R-390] R-391 stuck slug screws

[Mack McCormick]

I'm repairing/aligning a R-391 for a friend. Every single RF deck slug
tuning screw is solidly stuck. I think it is a galvanic response between
the brass and steel.

Does anyone have tips to free the slugs? They won't budge using a moderate
amount of force. I've used PB Blaster and heat to no avail.

I've repaired at least one hundred 389/390/390a/391 over the years but this
is the first one I've encountered with every slug stuck.

Thanks in advance for any ideas.

73,

Mack
W4AX
https://www.qrz.com/db/w4ax