I have an old Ideal Mexico system boiler. I have not had it serviced for a few years and I know it should be serviced. Yesterday the boiler did not light. I could hear the spark clicking repeatedly but after 10 minutes it still had not lit. So I assumed it was dead. I called a engineer. Today I tried the boiler again and it works. The ignition comes on first click but latter on I noticed it takes a few clicks to ignite. Anyway, warm again. Engineer arrives and takes off front ONLY (just the white case) Looks at working boiler and turns the temp knob back and forth and states that the gas valve is likely needing replacement, the Spark PCB likely needs replacement, and the control knob is not properly working. He recommends a new boiler as the replacement parts are going to be costly. Now I KNOW a new boiler will be cheaper to run, but as I am trying to sell the house it is not an investment I want to make. HOWEVER I have to question how the engineer can determine that the gas valve needs replaceing without looking at it, not why the spark PCB needs replacing as it is clearly working. He said that it is on the way out and the spark is no longer big enough. Am I being given a tall tale?