[R-390] AGC..Z503 stuck slug

[Bob Login]

Hi,  Working on a 390A with low agc voltage. As 455kc signal
is increased the agc voltage goes from positive 1v to negative
but take plenty of signal. Checked everything in both rf & if decks.
All components looked ok. So tried to peak Z503 and seemed to work
but slug seemed stuck after a few turns. Put some WD on threads
and tried again with plastic tool...it broke off...really feel bad about that!
Any suggestions....or someone out there willing to part with a replacement?
Thanks & 73 Bob, AA8A