[Repeater-Builder] Duplexer cavity repair

[tomnevue]

I bought a Sinclair Q202G 4 can VHF duplexer. The previous owner 
clearly spent a lot of time playing with the variable capacitors. 2 are 
totally ruined and I suspect the other 2 are damaged because I can't 
get a notch depth below 60db and it's not stable. These are porcelain 
(white glass) piston style marked MAV05A30.  Can anyone help me with 
some replacements or source of supply?  Any help is appreciated.  Tom  
W2MN