Diode replaced, problem solved. Lets hope it stays that way. Thank you everyone!

I have now received the diode from Yachadem, Thanks. To be certain, before I replace, The black stripe is the cathode? and goes to the collector of the transistor? in the circuit snippet above.

Hi Menahem, I have plenty of 4148's but not the other type. Assuming they are cheap to post can I buy 2 from you? please send a PM with a price. Thanks

Thanks everyone. On the power transformer it says GR4002 type 5514. Attached is a picture of the underside. You can see the hole where the chassis screw went and broke the diode! Again the biro points to the position of the diode. Hopefully someone else with a 4002 in bits will have one of these D17's intact as there is not enough to see. What I

Hi Its the one pointed to by the biro. The symbol on the underside is for a Zener

OK - I have now dismantled the deck and diode D 17 is physically broken. It was bent over the power transistor (presumably from manufacture) and moving the deck must have caused an impact! It is a BZX79 15V Zener 5%. The nearest I can find is 16 V which is too much. Can anyone help. Happy to pay- send a PM Not sure if this is the problem but it can

OK the sensor is producing an output back to the board under the deck. I notice the manual raise/lower switch will not lower the arm either. Where do I look next? Thanks

just to bump this up, does anyone know which wires to test for an output from the detector arm? Thanks

Well the problem has returned.There seem to be 4 wires coming out of the detector arm. The manual is not clear which provide the signal. could you advise which colour wires to test between and what sort of voltage to expect. Thanks

Problem was a bad connection to the solenoid. Re-soldering seems to have cured the problem