On the G1800/G1900, you turn the key to Run and then preheat is just halfway between Run and Start. My glowplug light doesn't come on, but oil pressure and battery lamps get dim. I hold the key in the preheat position for 5-10 seconds and then turn it completely to start. The engine fires off every time. If I don't preheat, the engine puffs smoke and won't start even in the summer. Surely Zina has discovered this by now. There is a screen below the steering wheel that is removed with two thumb screws. Under that cover is a 3-fuse block. Perhaps the 20 amp fuse for the glowplugs is blown. There are four slots in the fuse block, but only 3 are used. The one in the middle should be a 20 A fuse for the glowplugs. The glowplugs work off the ignition switch. They are not controlled by the combination box like many other items.
BTW: When I go to Run on my ignition, I immediately hear the tick-tick-tick of the fuel pump. If you don't hear that, you might need to replace it.
Zina, the Kubota forum would have been the ideal place for your post instead of here. Nobody has time to read every post in every forum, so to get a quick response, you need to make sure your post is read by the most experts. I'm thinking that in 9 years, you got your mower fixed, sold it, or it has collected a lot of dust.