"But this is the sort of thing that unless you do the work yourself and you have reasonable mechanical skills, having someone else to the work is probably not going to be economical. And FWIW that type of skill is rapidly going the away in this country."
However if machine work is required , a boat yard "mechanic" would be a disaster.
IF you can, take it apart , and see whats needed , then reassemble very loosely .
I suggest a Hyd shop .
They are used to diverse repairs and rebuilds.They have standby time waiting for the breakdown repairs "on the quick" that pay the bills.
SO tell them that its an infill project , you don't need it for a couple of months.
Frequently the labor cost will be minor.