2.5 Merc Fly Wheel coming loose
 

Today while running my R.P.M.'s seemed to bounce around wildly & then my engine just died. After returning to port on the other two engines I opened the cowling to find that all the nuts & bolts holding the fly wheel had worn loose or broken off. One of the bolts then cut the wiring which caused the engine to cut out.

The engine still seems to have compression & moves in and out of gear.

Is this a case of the last mechanic working on it didn't properly tighten these, or do I likely have a bigger problem, if so what?