After 8 trouble free years my Aiwa HV-MX1 VCR has started having
intermittent problems with FF and REW. Sometimes it works fine other
times it will not FF or REW.

When it fails the take up spool (terminology?) will spin slower than
normal and the free running spool (terminology?) will have the brake
applied. The brake is stronger that the take up so the tape does not
move at all. The mechanism, however, continues to try and drive it
until you intervene. Simply press STOP and it may work properly on the
next try.

Anyone got any ideas what may be causing this behaviour. Is it likely
a logic issue i.e. the processor or a feedback problem i.e. mode
switch or something else altogether?

All other functions appear to work correctly.

TIA,
Dave