My M41 overdrive gearbox (J-type I believe) was an exchange reconditioned item about a year ago, but yesterday on the motorway the OD just disengaged.

The OD panel light is working, and I can hear the solenoid clicking underneath when I have the car at rest in 4th gear and operate the switch. My previous car (old OD which hadn't been worked on) used to lose OD due to a mixture of low oil and just old age, but it used to be working again after a few hours to cool down. But this one is still not functioning the next day and of course shouldn't be suffering old-age symptoms quite yet.

Could you tell me what my likely culprits are? I hope to do a multi-meter test in the next few days, but if the solenoid is clicking, could it still be electrical?

Thanks a lot, Tom