'90 Prelude ABS question

At 144K miles now; and the ABS, although apparently still functional,
turns the charging motor on/off constantly while driving. I am
guessing the system is losing pressure and keeps needing to recharge
itself. But is this something other ABS owners have experienced and
can give any further details? Is there any service beyond a complete
ABS overhaul, which is all Honda had to say on the subject (something
like an $1100 repair btw)? My local mechanic doesn't want to touch
ABS.