Why even mess with the silicone sealant? I'd say the odds are decent that you will mess up the tach amp that way, make a good amp into a bad one.

__________________
Respectfully,
/s/
M. Dillon
'87 124.193 (300TD) "White Whale", ~392k miles, 3.5l IP fitted
'95 124.131 (E300) "Sapphire", 380k miles
'73 Balboa 20 "Sanctification"
Charleston SC