OT Coleman Generator Question

I bought a 5000w Coleman powermate generator recently and didn't pay a lot for it. I tested it before I bought it and brought it home and started the engine. It ran fine for a few minutes and then threw a lot of sparks out of the powerhead but I couldn't tell where they were coming from since they did not last long. I'm not sure what it did to the powerhead, but the engine is now lugging hard. Does anyone have any ideas where to start to repair it, or should I just replace the powerhead or the whole generator?

Could be the "permanently lubricated" needle bearing in the generator head has seized and spun. When it fails it lets the armature rub on the field poles causing drag/sparking.

To inspect, remove the thru bolts holding the generator head together then carefully pull off the end bell (watch for the pair brushes that will pop free as the end bell comes off). The bearing is pressed into the plastic end bell. Unfortunately when it fails it usually destroys the end bell.

Does it usually damage the armature and field poles beyond repair or can I replace the bearing and end bell to repair it?

So long as the generator did not run too long with the armature rubbing it'll simply "shine up" the armature poles and field shoes a bit - there should be no permanent damage. Be sure to blow out any metal shavings, etc. inside however!

A bigger concern is the molded plastic end bell. If the bearing has spun it likely chewed up the bearing cavity which generally ruins the end bell. Unfortunately the only fix is replacement

It ran less than 5 minutes after the failure, probably less than 3. It looks like an endbell is not too expensive so if that's all I have to replace I'll still have less in the generator than they are usually going for.

I just did a little more investigation and was heartened by what I found. It only took a minute or two to pull the endbell off and I found the bearing intact but a little worn/loose. When I looked at the stator and rotor, they didn't touch long enough to even knock the rust off. the brushes look good, but it looks like the rotor moved back because the insulation is worn off of the wires going to the outlets in a few places as if the plate that the brushes ride on was moving back and rubbing on them. All the other wires look good and there appears to be no damage. You would swear that a mouse had gnawed the insulation off the wires if the cracks were big enough for one to fit through the way the wires look. The plastic housing is not damaged so I am going to try to order a bearing online and replace the damaged wires. I hope that will fix the problem. I hate to junk the machine since it appears to be otherwise in good shape and hasn't even been run enough to get the muffler rusty all over. If anyone has anymore insights, I would certainly appreciate them and I am grateful for the help so far. It certainly pointed me in the right direction to start figuring out the problem.

I have seen bearing failures before on gensets. Most of the time you can just replace the bearing and be fine. Or in your case the bearing housing.Rotor and Stator failure caused by this. Is not as common as people think. You probably will be ok