[Drake] TR7 Low Pass Filter disassembling?

[ik2bcp - Guido Tedeschi]

Ciao a tutti (Hi to all),
    after fixing some days ago, with your invaluable help, the TR7 of  my 
friend, now it is again the turn of my TR7, the one that was "touched" by a 
lightning.
About two years ago, I have begun to fix it, many components were damaged, 
and, after a pause of more than one year, this evening I decided to "attack" 
it again...
I need to check and, probably, substitute the transistor Q1901 (2N3906) that 
switches the relay K1901 on the front Low Pass Filters Switch board.
I removed the bandswitch shaft and the three ground straps screws, but I'm 
not able to remove the Low Pass Filter boards, there is always a metallic 
standoff that blocks one board with a rubber ring :-(
Any suggestion and/or trick?
Thanks and 73
Ciao
Guido, ik2bcp