Dear All.
Thank you for the great response to this problem and over the course of the next couple of days I will investigate all suggestions.
As always this site comes up with the goods.
Regards Bill 👍

I am sorry to say that I cannot find any data about this ESC, and not even one for sale on EBay.
There are very few tests that can be done externally unless the casing can be removed, and these are of limited use without access to repair. Your best tool is eyes. As you do not mention anything heating up, an open circuit is a likely possibility
Its worth while carefully inspecting the wires for cracks near the casing, they break where they bend, especially the thin servo wires. Check these in the connector in case one has become separated from the crimp. One does tend to pull the wires rather than be able to grasp the connector.
Old black wires can degrade, somehow the external insulation reacts with the copper. I've seen this happen with wire stored in my workshop. The copper goes black and is practically unusable. It makes a poor connection and is difficult if not impossible to solder. So look closely at all black wires.
If it contains a processor and is very old, its not impossible that the memory has aged and become faulty depending on the storage technology. Some parts from the 90s were only specified for a ten year life.
Try a substitute and if that works then at least you have some sort of answer. But do recheck all the wiring polarities first just in case someting has gone adrift.

I've had the same problem with the same esc Bill,
what I finally found, was the two wires that go to the switch, they have shrink plastic round them, one of my wires had broken inside the shrink wrap, it was just patience and luck that I found it,maybe it's the same on yours, you will need to remove the shrink wrap, de-solder the wire then re-solder and shrink wrap ...Both wires! hope it works.🤞

Cheers, Pete

Hi Bill,
What may also be important is-
What else did you change / upgrade / rewire in the course of your refit?
Have you tried it on a simple Servo Tester?
Does it need to be 're-trained' from the TX for High / Neutral / Reverse?
Cheers, Doug😎

It looks like it has an on/of switch, is that working ok ?
Have you been able to see if there are any breaks in the wiring. ?

Martin555.

Hi CB90.
Thanks for your reply.really appreciate it.
Yep I have already tried that and the contacts are free,so no problem there.
I wish it was that simple 🤔☹️
Bill.

Hi Scratchbuilder,
Looking at this ESC it appears to have a miniature relay.
It could get jammed or the contacts stick together.
may sound strange but have you tried some percussion testing (tap it).
regards