Hi guys,I have new to me L2900.Tractor runs great,but the glow plug light/timer seems to have a mind of its own.Sometimes when I start it cold,light comes on briefly like it's supposed tther time it comes on and stays on for several minutes,till I shut the tractor off and restart it.It has also come on after its been running a while,and same thing,I shut the tractor off and restart it to get the light to go out.Glow plugs seem to work good,this thing will start easily in constant below freezing weather.I've done a little searching here,but I want confirm my problem before I spend the money.Do I need a glow plug controller?If so,where is it,and how much are they?Thanks.