How often do you have to service your Studer or Otari deck ? Home not pro environment.

I had my Otari MX55N serviced some 4+ years ago and biased for current tape formulations.  Still going strong and measures fine.  It is in an audio (non-pro environment).

i had a couple of revox B77 i use in a mobile recording rack, proved so reliable that i sold spare to a very high end shop in San Diego..they use it with a protection copy Jacintha tape for demo...it sounds excellent 
ATR tape high speed big reels iec EQ
good techs abound on West Coast seattle to san diego because of the studio demand...

what are you seeking to do ?

the machine is the inexpensive bit........

Two things - hunting for master tape dubs and making compilations off records and even maybe some cds.

Restoring Revox A77's is expensive. I sent mine to the national service center in Nashville years ago, and the restoration cost me more than the A77. It's like servicing an old BMW; there comes a time when it no longer makes economic sense.