Got multimeter?.....Check to see if you are getting power to glow plugs, if not trace circuit back through any relays/switches/fuses till you find power, most likely problem is in general area where you first find power ... Wiring diagram for tractor will help....
There is a fuseable link that is attached to the glow plug bar, mine was on the first plug. Mine had intermittent power to the bar. There is a tab to unlock it and it wouldn't come off. After removing it from the post on the first plug, i would gat a hot reading with a test light and if it moved the light would go out. Its hard to see in the pic, but there was a little bit of melting on the plug/link. I replaced the fuseable link and she fired right up. It was $5 at the auto parts store
Mine is a 1526 but same issue. it was getting harder to start blowing white smoke and then it wouldn't start at all
It has been mentioned before about the quick disconnect on the glow plug rail melting. Mine was melted when I got it, and when I read about it on here. I checked mine, and caused it to stop working. i cleaned it up and slid it back on. that was 8 months ago. Last couple times I went to start...