From the underslung MRH picture post 207, it would appear that the MGB Flared housing is missing from the Lift housing of the MRH shaft. Lack of lubrication to the mast bearings may be an issue, I believe on this model there is no way of verifying oil supply as there was on the 332 post MRH replacement. But HUMS should have picked this up.
There is also the barrel nut possibility, but I can’t see it causing drastic damage in such a short period of time.