My old Ideal Mexico super 2 RS60 has developed an issue where the heating/hot water has become intermittent. I've tested power to the gas valves solenoid which is a steady 248v ac when the controls are calling for heat but the solenoid doesn't seem to have enough pull to suck in the plunger. So my question do the solenoids usually fail completely or can they go week. My solenoid does still have have some magnetic pull but seems weak to me but I don't know how much pull it should have. Another thought is could the plunger be sticking.