Blower question

I recently picked up a Buffalo forge blower at a junkyard recently. It was rusted up and nothing would turn.

I removed the blower casing and the fan. They're in servicable condition.

I opened the gearbox, and sprayed down the contact surfaces with PB blaster. It got quite a bit of rust out, but the gears will still not turn. The largest gear can be "rocked" laterally away from the smaller gear just a bit, so I know it is not frozen to the gear it touches.

Clearly, something else needs to be done. I found and removed a couple of set screws in what look like old-style bearings, but it did not make a difference. The gears are all in good shape, and it seems like there is likely something simple that needs to be adjusted or replaced in order to get the gearbox working again.

Take a look at these pictures:

Here's the outside of the gearbox. I put the side cover back on temporarily for the pictures.

Here's the inside of the gearbox:

The camera makes it look a lot more rusty than it is. I ran it through my electrolytic derusting tank, and got a lot of rust out that way, but I didn't spray it down with oil afterward, so there's a very thin layer of orange rust over the inside surface.

I'm guessing that one or more of the bearings has frozen. Are these poured bearings, and if so, how do I replace them?

Thanks,

TMIB