Ok, thanks for replies, the overdrive switch is on the dash and proves good,as for the inhibitor switch I tested this one by bypassing it, making certain not to select reverse with overdrive engaged. The problem of sometimes slipping overdrive and occasional non engagment, and sometimes not disengaging remained, although this switch is slightly faulty as it occasionally has closed circuit in first and secound positions.
Am going to check filter today, and have also read about clutch remains trapped here, and the need for regular oil changes.
Solinoid faults, I think we may have an issue here as this car pops and backfires occasionally when overdrive is activated, could a faulty solinoid draw current away from the ignition?
Cheers Phrom fill.