Issues with Ampeg SVT 350H

I'm having the exact same issues with my Ampeg 350H head and the cooling fan circuit in it, as this previous post showed:
http://www.groupdiy.com/index.php?topic=39622.0
Although the solution was never posted.

I've tested the fan with a 9 volt battery at it worked fine. I've also replaced the 220uf capacitor (C17) with no changes.
The fan will move just a tad whenever the connection is made with the power on (about 5% of a full rotation).

Does anyone know how I can fix this? Local repair shops are too expensive.

I'm sorry I can't exactly remember how I fixed it.
It might have been the transistor TIP31c that had blown??
It's also possible I replaced the resistor at the base of the transistor?

Thanks.
I'll try replacing those as soon as I can get a hold of the parts.
I'll let you know how it goes.

Well, I've replaced the transistor and the resistor at it's base.
Still no luck.
I'm beginning to think this could all be the fan, although I haven't been able to find an exact replacement.
Anyone know any fan I could buy to replace this one?
Here are the specs printed on it:

Comair Rotron
Sprint DC

Model: ST24A3
24 VDC
.14 A
3.3 W

Any help would be great;y appreciated.

First hit on Google for "comair rotron sprint st24a3":  http://www.talkbass.com/forum/f15/ampeg-svt-3-pro-fan-noise-143689/

Look about 3/4 of the way down the page.

Thanks!
Looks like I'll be buying the ball bearing one from Digikey, as the other links are broken.
Still, this is a big help. I hope the problem is just the fan.

Well I had the fan tested and it's working fine.
Think I'll just have to bring it to a repair shop at this point.

I appreciate everyone's help though.