Now, the starter 'click' problem.
With all the stops in the start circuit, you're getting a severe voltage drop before it gets to the solenoid. Brake switch, seat safety switch, pto safety switch, ignition. Lots of breaks in that circuit. After a while, corrosion gets the best of it. We could tear the whole darn thing apart, but have you looked behind the dash? You'd think they were planning on adding NASA guidance controls to it somewhere along the line.
Anywho, you need a cheap 4 prong 30 amp relay from the auto parts store. Lights, horn, accessory, etc, relay. Get one that has a metal mounting tab with one hole on the opposite end of the electrical connections. The numbers of the 4 connections on the other end of the one I used were numbered #30, #85, #86, #87. A good in-line 12 volt fuse and holder, and some crimp connectors will round out the supplies needed list.
There is a bolt just to the right of the top of the starter you can use to hang the relay, or the bolt that holds the dipstick tube onto the engine.
Now, to hook it up. The #85 terminal on the new relay is the ground. If I remember right, I grounded to one of the hood hinge bolts on mine.
The #30 terminal is the power in. Run a wire from the large nut on the solenoid, to the inline fuse, and then to the #30.
Now the 'fix'.
Remove the wire coming from the ignition switch to the outermost terminal on the solenoid. The one in the bottom center of this pic, with the black connector and red wire:
On my 185, that wire was purple if I remember right. Set that wire aside, and now run a wire from the #87 terminal on the new relay to where that wire used to connect, on the solenoid.
The wire from the ignition switch that you pulled off from there, connect a new wire to that to run to the #86 terminal on the new relay.
That should do it.
Here's a better pic of the relay installed: