My LX280 mows perfectly for about 15 minutes then the blades disengage. The mower keeps running, only the blades quit. If I let it cool down I can run it for another 15 minutes. I suspected that the electric clutch was going out so I replaced that. But I have the same problem with the new clutch. Any ideas?

Additional info: Both clutches were very hot after mowing. I'm not sure if that is normal.

 

It could be the switch contacts getting hot and losing connection. I'd check for power to and from the PTO switch.