Re: Troy bilt field coil part no. 1754151
From a quick Google search I read it was manufactured by GardenWay and they went bankrupt.
As others said before me: All trails lead to the big "unavailable".
MTD lists it as "No longer available"
Apparently it was a $250 part, so that's quite a chunk of change to drop into a used machine. I suspect your only option is finding a used one. It was widely used, so probably a shop would have one in it's graveyard of junked machines. Try e-bay also....Ya just never know.
I feel for you, buddy. Sucks when this stuff happens.