Thanks, but definitely not fearless... at least not as much as I used to be, for sure! It's just that my lawn is getting taller and I'll be da$#@ed if I'll pay somebody close to $200 to mow it for me, and I'm having doubts about how soon I'll get those factory parts. Necessity often gets me motivated! (Hey, I may be cheap, but I'm CHEAP!!)
Now when it comes to one of my "restoration" projects, a 1971 Honda CB 100 (yeah, a 100, a real monster) that I just got running fairly well recently... yesterday the kickstarter shaft broke clean off. That means a full engine removal, tear-down and case split, and I'm not really sure if I want to tackle that. Just don't have the confidence I used to! (Getting lazy in my old age??)
As far as preventive maintenance on the motor mounts... no maintenance, but it might pay to take a look at them every now & then. You're right, I'm sure one broke initially, placed more stress on the remaining mounts, and progressed from there. Still not sure why, however; just wish I'd picked up on it sooner.
As far as damage due to the engine shifting, no, at least not that I could see. My biggest concern was the driveshaft, connected directly to the engine crankshaft, that goes under the floor to operate the main hydraulic pump (the one with the plastic fan on it). Fortunately, there's --apparently-- enough splined-shaft length in there that it didn't pull out completely. Now THAT would have created some REAL issues -- I shudder to think of that scenario!