Engine dies when blades engage

New guy here...

I inherited a Dixon Ram 50 from my BIL. The mower starts up and runs great. Will go forward and reverse. But when I pull the PTO button up, the mower dies. I can see the spindles that the belt runs around start to spin before the engine dies. From the research I have done so far I think I will start with the seat safety switch, but wanted to get some other input.

I have searched for an ID plate to get a model/year but have struck out so far. I believe that it is in the 04/05 range with a 22hp Briggs and Stratton motor.

Any help/ideas are greatly appreciated.

Not the seat switch.
The same pair of contacts switch off the engine when you try to move without being in the seat as shuts down if you turn the blades on & are not in the seat.
How is the battery ?
If the battery is low, the load on it when your turn the blades on will cause the fuel solenoid to shut, stopping the engine .
A blown head gasket can do the same thing as can a lazy cylinder that is not working.

So start by running the engine, set the hand brake then go round the back and remove one spark plug.
If both are working, the engine will slow down a little but keep running.
Try this with both plugs.

No joy there then hook up some jumpers to a known good battery & try again.
Problem goes away = charging problem.

After that you are looking at the switch itself.
2 prongs are used for the cranking circuit and 2 are used for switching the PTO.
All the others are kill wires.

Ok I will give those things a try.

I did notice when the engine is not running and I pull up on the PTO button I can hear something click/engage.

Battery has been hooked up to a battery tender and shows full charge.

Not sure exactly what the problem was, but it works now.

I started with running jumper cables from the car to the lawn mower, no change. It still dies when engaging the PTO.

Next I took each plug out and the motor bogged down a bit but stayed running.

I then unhooked the seat safety switch and plugged it back in, then I took the panel where the throttle, choke, etc. are and unhooked and reconnected things under there. When I put everything back together and tried, the blades engaged and the motor stayed running.

Sounds very much like a bad connection.
Glad you have it running and thanks for the follow up.

Thank you for the suggestions!