I have an early 90's Viessmann BEA boiler with the analog clock Trimatik controller. It has always been issue-free but now will no longer fire. If I jump the T-T terminals the burner works, so I know the issue is not with the burner. Placing a pen in the overide switch hole on the Trimatik is supposed to make it run up the the high limit, but it does nothing other than activate the circulator relays in my case. I'm not sure which sensor controls the high limit, but there is a boiler temp sensor that reads about 140 ohms and seems to increase with the water temp so I assume that is working. I've been told that the issue is likely the Trimatik itself, and the only hope is to replace it with a newer controller for $1300 in parts. Is there anyhting else that I should look for to confirm that it is the controller? If I have to do the upgrade, how difficult is it? None of the local Viessmann service techs I have talked to have ever done the conversion so I'm a little concerned. I can get by for a few days by manually firing the boiler for hot water, but need to resolve this soon. Thanks in advance for any help.