I have an old hearthstone (sterling) propane gas stove that when lighting the pilot this season, lit fine, but the actual dial after depression and holding for a minute, refused to pop back out so I could dial it to the "on" position. It eventually did release on its own ( within the minute or two of me checking the thermostat ) but since it didn't "pop" immediately(did it twice) like it has in the past, I shut it all down again. Any thoughts on what needs to be replaced?