Transmission leak

[horseplay]

I have a 2007 340 Sundancer w/ 8.1 L mercruiser engines, ZF Hurth transmissions, and v- drives. I recently had the boat out for a bottom paint job and to check the shaft seals. After a short run across the lake a problem occurred. Port side transmission was making a loud noise and vibration. Transmission fluid was leaking into the bilge and 3 of the 4 coupler bolts were sheared on the front of the transmission. I replaced the bolts and the transmission still leaks fluid in neutral. I noticed that the lip on the transmission face behind the coupler is severely worn down from one bolt/nut that was rubbing against the face of the transmission after the head of the bolt sheared off. I suspect the seal was damaged.
So, does the transmission need to be pulled to change out the front seal? Should I also change out the face plate of the transmission if possible?
Could someone have loosened or removed the bolts to check the shaft seals and forgot to tighten them? The bolt with the nut attached did not have the lock washer on the nut side. The
only remaining bolt and nut were easily loosened with very little effort.
Thanks in advance for any help!

 

[LG111]

Sorry about the trany trouble! Those bolts don't just come loose. Sounds fishy. For the front and rear seals. Yes the boat most likely needs to be hauled so the shaft can be pulled back and trany pulled. Had that done on my 410 last summer. New trany. Basic labor out and in was approx 10 hours. Total was 16 as i had extra work done that was not planned. Like new dripless systems on both shafts.