I had a funky problem on my '72 Cub backhoe, "Bugs". I lent him to a friend, and when I got him back, the comment was, "it will always start if I get things just right, and hit it with a shot of starting fluid...."
I had never had this problem, though at times, Bugs could be temeramental to start. I remembered, also, that sometimes the engine seemed to ctach and start start as I released the keyswitch from the start(cranking) position to the ON position.
I did a little detective work with mty friend Alex, and sure enough, the ignition switch was faulty-it would "almost always" not supply any voltage to the coil, while cranking. Then on releasing the switch from the "Start" position, it would "almost always" begin to supply the 12V to the coil. the condition started out as very intermittent, and has gotten worse over the last few years. I had never seen this problem described on teh board, so I wanted to pass it on in case someone else has a similar problem.
So I wanted to replace the switch. The one ion teh tractor was not stock, and I didn't want to pay the $35 that a stock switch would cost, so I checked out Tractor Supply, and they had a Universal switch that looked like it would work, for $14.99, in the "tractor" section of the store.:http://www.tractorsupply.com/agriculture-farming-ranching/tractor-tune-up-repair/tractor-tune-up-parts/tractor-electrical-system-parts/universal-start-switch-with-2-keys-1831705
I picked one up, and on a whim, I checked in teh Automotive aisle, and found there a very similar-looking switch, with the only differences being that the Automtive switch was about 3/8"-1/2" deeper overall, and it only cost $7.99. I can't find this switch on the TSC website.
I didn't buy the cheaper switch, as I couldn;t recall how much clearance it needed behind the dash, but I wanted to pass on that after installing the $14.99 switch, I am certain that the $7.99 one would do as well, and would have no problem with clearance.