Toro ZTR Kohler engine Rectifier and no spark.

This is a Toro ZTR with a Kohler commander engine
I've had various issues with it recently from the Repairing a Beater thread.
This time it stopped charging the battery but got back to work after an overnight charge.
I had time for a look at it this morning and trying to check the volt regulator /. Rectifier I have no volts showing across any 2 of the 3 connections. Also infinity if I measure Ohms from any of the connections to the mower frame.
I believed that told me the rectifier was toast, so I have ordered a replacement. But the mower was to be used this morning so off it went with the freshly charged battery.
Ran till lunch no concerns, but when the operator stopped for lunch it would not restart.
Engine spins well but their seems to be no spark, also it has melted a hole in the back of the rectifier connection.
Hopefully when I get the new rectifier it will,solve the no spark problem. Or it's back to checking the coils again.
Thoughts?

1) The charging circuit and the ignition circuit have nothing to do with each other

The 2 white wires on the 3 pin plug are connected to the stator so with the engine running they should show 28 to 48 V AC between them .
If not your alternator is stuffed.
The purple wire in the middle is the rectified DC power going back to recharge the battery &/or power the electric PTO.
Your rectifier is stuffed and the battery is trying to turn the alternator into a really bad electric motor turning to opposite direction to the engine.

Once the battery is recharged the mower should run , but disconnect the rectifier plug and you should be able to run the mower like that forever you will just have to keep on recharging the battery and running the mower till the battery is dead flat will wreck the battery.
Got a few customers who run their mowers like that because they don't want to fork out the money for a new alternator

If it won't spark at the plugs check the fuses and relays.
If it has a cut out relay that defaults to off, then that needs power to turn th magneto on ( break the kill wires contact with ground )

Thankyou Bert, from what you are saying that sounds like you have nailed it.

It has a cut out relay that defaults to off, then that needs power to turn th magneto on ( break the kill wires contact with ground )

From what I remember I have replaced the ignition relay before as it's cover was smashed.

How would I identify the Kill wire?

I have ordered a new rectifier as that's what the boss wanted, it will be here Monday, but it sounds as if that may not solve my problem because the engine will not spark even with the rectifier unplugged.
The piece I have ordered is in the picture, I also ordered a replacement for the connector which got burnt/ melted.

I also noticed that the right mounting bolt is missing.This is the ground connection and if that falls out the rectifier will not ground properly.
The intermittant grounding can also cause the wires to overheat.

When fitting these I always put an earth strap on both sides of the rectifier and pop a star washer under the bolt to stop it from vibrating out.

Thank you Bert

I replaced the rectifier and its connector, charged the battery. It fired then died, but at least I had spark.
Started at the beginning again, and found some dirt in a large wiring connector. After cleaning that it fired and ran well.
Thank you all very much.