My stove is making a whining sound.

I start hearing a whining sound about 15 minutes after I turn my stove on.

Does the whining sound vary when you change the speed of the room blower?

Yes, it does.

That means the bearings are wearing out in your convection blower. Try lubricating the bearings with synthetic bearing oil.

https://www.eastcoasthearth.com/products/anderol-465-synthetic-bearing-oil-for-pellet-stove-motors-1-7-oz-bottle

If the noise comes back after a few days, you need purchase a new convection blower.

Okay, I'll try the oil first and go from there. Thanks for your help.