I appreciate the effort. That manual is for a model beginning with ZFC, and mine is simply Z… I tried anyway, despite generally refusing to deal with the manual cartels. I could not get past the reCAPTCHA forced by manualslib. But I doubt it would help anyway. What I need is a service manual containing the resistence measurements. User manuals never have that info. The slightly different manual that I have (ZD 19/4 D) does not have anything useful.

Regarding fixpart.co.uk, I just get 403 forbidden on that site.

I’m not sure to what degree it helps, but if your problem with acquiring a part is geographical in nature I’m in Ireland, and am happy to get and mail the part for you if it is available in either EU or the UK. Good luck and keep us posted!

I appreciate the generous offer! I’ll keep that in mind but I will first try to diagnose more precisely which part I need… whether it is the relay or the thermostat. Then I will try to find it locally. If it’s the relay then I’m probably toast. But I might see if something universal can be rigged up.