I'd like to replace my clockwork timer with a more sophisticated 2-channel 7-day timeSWITCH 140. The plumber who installed the boiler said that the timer is basically "plug-and-play" so I have just received my new timer and it does look as though it should be quite straight forward. A few clips on the side and 5 long pins on the back to locate inside the boiler. I just wondered if anyone could offer any hints or tips before I start trying to pull the old timer out of my boiler?