3.6 Case through-bolt o-ring leak

[RSstop]

Need advice on solving a leak at case through-bolt o-ring.
History: Purchased fully rebuilt 964 3.6 engine. Installed in car. Runs great! DRIP. DRIP, DRIP, driver's side o-rings leak badly. Builder must have cut the o-rings during assembly.
My plan is to remove engine/ heads/ air cooling shields to access both sides of the case thru-bolts, replace the bolt o-rings one at a time, hopefully without disturbing the cylinders/ rings.

Any words of advice so I can avoid the same mistake by this "reputable engine builder" ? Where can I get o-rings? Pelican doesn't list the o-rings separate. Hopefully these are not the cheap "blue" Victor Reinz o-rings that come in the 2.0 to 3.2 911 kits?
Coaching encouraged! Thanks
Lyn

[Gunter]

It seems that the O-rings can get distorted when tightening the trough-bolts. The beeech is that you cannot get at them.
What is the general practise? Just use oil on the O-rings when tightening? RTV Silicon sealant recommended by Wayne in his book?
I remember people mentioning green Viton O-rings instead of blue?
Is the leak coming from the nut-side?

[john walker's workshop]

the P+Cs need to come off to deal with the o-rings. green viton only! never use the blue ones for anything. call around to the local shops to find them.