[TR] Type A overdrive question

[ron landis]

List.  I have a type A OD on my TR250.  It is from an Austin Healy.  On
occasion the OD will not "kick in", when I hit the switch.  I t appears the
solenoid is not working.  Then by magic it starts working.  I have replaced
the solenoid, relay under the hood, and the 3/4 th gear switch on the
transmission, also checked the spacers, and checked the Ground wire.  

Any
Ideas??

Thanks
Ron