I'm hearing a buzzing from a VR8204c3007 gas valve on my Burnham hot water boiler. (Boiler was installed in early 1990s, I think 1993). I've been in the house for four years so I don't know if the gas valve is original. This valve buzzed intermittently last winter, and this morning was the first time I noticed it this winter - we've been in a severe cold snap here in Minnesota for the last week so my boiler's been working overtime. The indicator lights (yellow and green) are both in the "heartbeat" pattern so it's no clear indication of a problem, but I'm also not eager for my boiler to die! Should I be preventative and call a heating tech to just replace it?