Electronic interval timer for SLX, 6002, 6006, 2000, 3003

[John Wild]

Does anyone have information on the repair of the interval timer for the 3000/6000 cameras produced circa 1982/1983. I have bought one 'as seen' and the minutes/seconds - hours/minutes switch does not change the time period (it only works in minutes/hours mode). The slide switch is not faulty.
A circuit diagram/repair manual would be great. The factory cannot offer any help...
The wave soldering is rubbish so it could be a 'dry' joint (or lots of them!) alternatively a transistor is not switching off; but which one?...
See Ebay 280486115297 for image
Thanks for any help on this.

John