Sounds to mee like they both need to find someone more familiar with hot the engines should be mounted to look at it in person.

My bet at this point... the holes are not drilled properly in the mount and the engine isn't even firmly bolted to the beams. Maybe they didn't cut out the fuselage's cheek cowl to clear the muffler (and/or the needle valve) and when they thing sttarted to bottom on that...t hey quit tightening the screws?

The last description he gave says to me that the engine shifted when he started it... that means the screws are loose.