I've been using my re-powered TB 2410 for a few years with its new engine and pulley setup. This year, I have noticed that either the belt or the pulley has been slipping, because once under a decent load, the auger and impeller would slow down, while the engine RPM remained steady. Once the load was relieved, the impeller and auger speed would increase back to normal.
So, this machine has been on the bench while my Toro PS 824 has taken center stage for snow removal.
I did the usual checking of belt condition and tension, then thought that the pulley itself may be slipping. I was originally thinking that the belt had become stretched or worn, but upon inspection, it looked really good. Then I thought to check the pulley.
The pulley that I have, since re-powering, is a bit oversized because of the 2X increase of power, and is coated with what looks to be epoxy paint of some sort (gray in picture). My thoughts were that the smooth epoxy surface was allowing a bit of slippage when under load, and the more it slipped, the worse the situation got.
My solution, which seems to have worked, was to sand the epoxy paint off of the 'V' grove surface of the pulley to expose bare metal. The machine now works properly, throwing snow a country mile.
Got it fixed just in time for the snowy weekend forecast for southern New England states this weekend (March 3, 2019).
I felt a bit concerned having only 1 good machine so far this winter, but now I am back to 2 good machines.