[TR] TR3A Odd overdrive behaviour

[Art McEwen]

The last couple of drives the first time I engage overdrive it works 
like a charm, but if I disengage it (be it 5 minutes or 25 minutes 
later) it won't reengage.   If I stop, even for only 5 minutes it's 
fine, but again, only once.

The gearbox oil was a bit low so I topped it up and that didn't change 
it.  I'm not stopping long enough for it to cool down so it's not likely 
heat.  If I drive without it for a while then try it doesn't engage so 
it's not like the solenoid is heating/cooling.

What do you think solenoid or internals?

I'm going to check the filter screen and re-top it up because it's been 
awhile since I've had warm 30weight running down my arm.