cracked bearing carrier????

[fs5]

I'm running a 12x20p merc cleaver on m y 55seapro.
I just recently had the carrier replaced because it cracked where the top bolt goes through and the bottom bolt vibrated loose.i was lucky not to loose the prop and all.
took the boat up the dam for a run yesterday and probably did about 25/30min run time .i pulled the boat and checked the carrier,the bolts were still tight ,but the carrier has cracked again where the top bolt goes through.
anyone got any ideas on what could be causing this?
has it happened to anyone else running a 55/60 merc?
the gearbox is not even a year old yet,and has done not quite 40 hours
thanks for any help.

[fs5]

should have said I got it fixed but it did it again .
heres a pic

[A/B Speedliner]

I am not familiar with this unit at all but it sounds like it could be a slightly bent shaft.
David