It looks to me like it wasn't properly engaging the ring gear.
Look at the wear marks.

no they were not. the bendixes were not popping out all the way. these starters probably started the engines less than 25 times to do this, btw.

replaced them with tiltons and have not had problem since. and they admitted to me they had issues with those starters.

MSD is caca
I am going back to OEM or I will try Pertronix

I’m currently just running the pertronix distributors mag PU and a coil. Ya I’m going to install my cd’s sometime soon as I have them new in the box but just a fyi current set up is flawless

I wonder if your MSD units are “Chinese Knockoffs” of “Chinese Knockoffs” manufactured on the graveyard shift. My biggest issue with MSD is the corrosion issue. I will be ordering MSD replacement springs and weighs to replace the rusted units. Otherwise I’m buying a used Mercruiser OEM distributor as a replacement

MSD = may soon die

Agree 100%. I just had a “new” coil go bad on the Mach 1 but what’s crazy is the ign box etc still up and running from back in the 80’s. The dist lasted a half dozen spins around the block and the coil lasted 12.

Tells you that they’ve gone china! Might as well just buy the cheap knock offs. The mag pick ups are identical fyi.