timing advance mechanism sticking made mess of starter/ring gear, no points

1989 5.7 350cid mercruiser s/n oc606793 . No Points in cap.
Recently bought a 23' carver, ran good for 3 runs then started running rough at ldle- in fact wouldn't sometimes. Hard to start, in fact took out starter (bendix gear stripped) and broke tooth off ringgear- Pull engine.
Haven't adjusted anything. Could it be the timing advance mechanism stuck in the wot position changing the timing at idle? Cap inside looks dry. Should I be able to move/rotate distributor rotor back and forth a bit (with engine off) indicating mechanism is operating properly? Or does anyone know how to check for proper timing advance operation?
I am going the right direction or could it be hydraulicing a bit from an exhust jacket leak? Just in the process of pulling engine. Thanks!!

Re: timing advance mechanism sticking made mess of starter/ring gear, no points

I had a V6 of about the same vintage. I do not remember if there was a mechanical advance in the distributor, but it will be obvious if it has it. It will be under the rotor and will consist of some springs and weights. Remember, ign system is Mercruiser specific, not GM.

You might post this in I/O section. Those guys are experts.

Re: timing advance mechanism sticking made mess of starter/ring gear, no points

Thank you for responding. I posted in wrong section. I will look under the rotor. I have new manifolds /risers/gaskets to install to eliminate hydraulicing. Will know more after the weekend, thanks again
Val