Are you checking the oil level? Both before you start initially and when it won't start hot? A little more description of just what is happening might help. The engine doesn't want to turn over or turns over but won't fire? There is a possibility that the carb float needle is leaking gas into the intake, then into the cylinder and on down into the oil (not good). However, you put on a new carb and it still does not do right. What you hear as dripping MAY be the hot muffler cooling and making cracking noises perhaps from running too hot due to partially sheared flywheel key or lean carb mixture.

I think I would be inclinded to check the flywheel key. You should be able to do that by removing the cooling shroud, the flywheel mut or bolt and washer and looking down the keyways to see that the keyway in the flywheel and crankshaft line up. Also, installing an inline gas shut off valve and using it when engine is not running might be a good idea.

I can send you a PDF of the Service Manual for that engine if you like. Address below, put in proper format and remind me, model number etc.

Walt Conner
wconner5 at frontier dot com

First started when I ran out of gas. I put gas in but would not start. I took off cover and then found a mouse nest. I don't know if that had anything to do with the tractor not restarting. I cleaned out nest and cleaned carb. Got it running. But when I shut down and tractor was hot I could not restart. And I would hear Botha drip and the crackling. Sounds like water in a broken faucet slow steady drip for 2 min. So I replaced the carb saturday and at first started but had the same issue that would not restart when hot. Then today won't start at all. When the mower gets a spark it starts for a second then shuts off. If I keep key turned it runs until I let go off key. Also, new carb had bolt at bottom which I left in. However, my old carb had the cut off selonoid. So today I took off bolt and put selonoid from old carb. Still not turning over only when key is turned.

I don't have a schematic for that, but it sounds like you have an OPR (Operator Presence Relay) malfunction.

Just guessing here. but---
I've seen some schematics where the seat switch is tied in to the OPR.
The OPR get's 12V in the run position, but not crank. (or vice versa, since they can be wire in a plethora of different ways to do the equivalent job)

Are you trying it with the Brake On?

That said, I don't know if your machine even has an OPR??

"If I keep key turned it runs until I let go off key"

I would locate and disconnect the "Kill Wire" and see what happens, even to the extent of disconnecting the "Kill Wires " at each of the two coils. The tricky "Kill wire" circuitry of these engines do quirky things. Your description above sounds like a key switch problem.

"And I would hear Botha drip and the crackling. Sounds like water in a broken faucet slow steady drip for 2 min."

I have never heard of such a thing.

Walt Conner

***"I took off cover and then found a mouse nest."***
I need to ask: What cover are you referring to??
Some folks refer to the tractor hood or "bonnet" as "the cover".
Typically on this forum "the cover" refers to the actual flywheel housing cover/fan shroud on the engine itself.
If you are referring to the hood..........and you found mouse nests material there..............there may be other nests or food caches under the flywheel cover of the engine. If there is any kind of obstruction located inside the flywheel cover your engine may be severely overheating due to the cooling fan air being blocked by whatever the obstruction consists of.
Severe overheating might explain the unusual sounds you are hearing on shut down.........and the refusal to restart hot.
If you have not already removed the actual flywheel cover from the engine you need to do so now, based on your statement about mice activity being discovered.
And hope the engine has not already been permanently damaged by overheating.

Got it running. Took apart carb. Checked pto. Checked plugs. I have to play with throttle and choke. One open one closed. Both open. Each time different combo. But generally after three tries it runs. So I know problem but gotta figure out correct settings. As for the drip the more I listen the more it is the sound of muffler cooling down. Thanks for your help and suggestions.