Ignition Problem

I have a Weil McLain 30 year old natural gas, one pipe steam system with electronic ignition. My problem is that intermittently, when the ignition clicks on the flame does not ignite. The clicking amounts vary. The other day it took 14 clicks before the flame lit. I noticed that this happens when it is colder out.
I have had the gas company over 5 times from December 2004 thru April this year with five different mechanics without results. They changed the gas valve, and pilot head. Cleaned the flame sensor and burner. I have another appointment with them on Nov 16th. I mentioned the G 60 Pak to one of them, without checking it, he said that was not the problem. Evidently they don't know the steam system Anybody have suggestions to what the cause might be ? Is there a way that I can check the G60 Pak ? Could it be the thermostat ? Help! Thanks.