G10 bolens

I have a 1979 ford 340 industreal diesel with a loader.It started good when i got it but last summer i left the key on a couple times now the manifold heater doesnt work so i replaced the heater plug but it still wont start unless i crank it to death or put in starting fluid witch it says not to .Now the air filter light used to come on when i turned the key to the heat spot but now it doesnt come on untill i get it going and rev it up?Is there a fuse or relay that may have burned out from leaveing the key on?Has anybody had this problem or now how to fix this?Please email me back if you have any info

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bolens G10 w/tiller,deck,plow,blower and cart,66 725 simplicity with tiller,blower,"32 deckand"42 deck.64 broadmower,1979 340 ford ind with loader 50 something henry backhoe and fransgaurd winch with a66 C60 chev dump to haul it all around