Pete, are you sure that the solenoid is faulty? A fairly common fault
in Xs is the solenoid not getting enough current to kick off due to
'classic' nature of the factory wiring. The previous owner of my '88
had been given all sorts of advice from garages about the need to
replace the solenoid/starter. Instead of this I followed some
excellent advice from the Seattle boys and fitted a relay that (7
years later) still lets my X start first time every time. Just a
thought.
Cheers
Dave