Ride on mower dies but immediately restarts when ignition cycled

Question on a ride on mower, a CastelGarden with a B&S 15.5 HP Diamond engine

Mower will start and run fine. At some point the engine cuts out. Simply turning ignition on and off (not engaging the starter) before the engine has slowed to a halt kicks it back into life. If it is not caught in time then it will immediately restart from the starter.

At times this happens every 10 seconds of running. It can go on like this for several minutes and then continue working without issue. Other times it will only fail every few minutes. Most often it does not play up until the engine is warm, but recently failed like this within the first few minutes of use. Previously I go the impression it would be more likely to start failing after using reverse, but this might not be true.

I have linked out the obvious safety switches to see if they were intermittent contact, but continued to fail (now reconnected). Have removed and run without the fuel cap and checked the filter. Nothing wrong with those.

Oil level is OK. I do get a feeling the engine runs hot, but I have no experience to compare it to. The vent box the exhaust passes through at the front gets red hot. But I assume if there is an over temperature switch then it would not allow instant restart.

Mower is pretty old, the hood is missing and also the cover to the control board (relays etc) It’s not unlikely there could be some corrosion on this board, but I would expect some hard failures and not just intermittent ones. Hydraulic drive, don’t think this is relevant, but who knows.

Scratching my head here. Have read all of the answers I find on the web but nothing exactly relates.

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