2146 Blowing Fuses

[ol'George]

Curve ball,
I've seen Batt-tree and udder wire ends dat lookie good on the outside, but where crimped onto the wire, there is corrosion or rust that prevents a good 'lectrical connection.
obviously, something is overloading the circuit.
You might have to check amp draw on that circuit and do some detective work. following the schematic closely, backtracking the circuit from the bat tree connection.

[ironman]

Looking at the wiring diagram, the battery input to the key switch is a black wire from the fuse to the "B" lug on the switch.
That input only over heats when you turn the key on (i.e. Run Position)
The only contact inside the switch from the "B" lug is to the "A" lug in "Run Position", or "A" plus "L" in "Run With Lights Position".
The key switches "A" lug (red wire) goes to:
1. the PTO
2. the center lug of the V/R
3. the reverse switch
4. the hour meter
5. the Low Oil Lamp.
The key switches "L" lug (blue wire) goes to:
1. the headlights
I would suggest to unplug the connectors to all the above mentioned items turn the key on and see if it overheats.
If it doe not, then start reconnecting plugs one at a time and observe, however if a plug passes test, unplug it again before moving to the next one. Hopefully you'll zero in.
With everything unplugged, if you continue to overheat I'd have to presume you have a short in the wiring harness, probably wires melted together from the same reason your fuseholder melted.