Dx 45 starter clicks.

[compact freak]

New starter. Thought same thing.

 

[flyerdan]

Get, or make one of those remote starter switches. Connect it to the hot lug on the starter and the terminal that the small wire from the key switch goes to. If it spins it over every time, the key switch is bad. If it still stutters, it's another issue, which could be a bad starter right out of the box. It's fairly common anymore, and often they will bench test fine but not when they have to engage the bendix with the flywheel gear.

 

[Spanner]

12.9 at cable at the starter. 11.6 at little wire at starter. Cables are tight at battery

As was said. You are starting at the wrong end. Go back to the battery. The figures above seem a little low.

Remove and clean the connections including the Ground connection at the chassis. (Do this. Don't just say 'They're good'). Then park a vehicle next to the tractor and connect Jumper Leads. Start the engine of the spare vehicle. You now have confirmed power at the battery.

Try starting the tractor.

If it starts - Your tractor battery is faulty (Assuming you have cleaned all the connectors).

If it doesn't start - re-take your voltage readngs at the starter (2) and the key switch (in & out) and report back.

Random swapping of components is not diagnostics. It's 'swapnostics' and gets tedious to read.