Chainsaw Repair

Hello,
Thanks to this site and everyone who reply's. I have had a very good running 288xp since I bought it now in 2001. I have serviced it and maintained it through the years with only the usual consumable parts replacement. Recently it quit oiling. I ordered an new oil pump and replaced it and it started back oiling for around 2 days. When I took the saw back apart the plastic oil pump drive gear was melted on the end and the seal was shot. Turning the gear on the oil pump I could feel a hard spot so I returned the pump for a replacement. I ordered a new drive gear, pulled out the hose from the oil tank and made sure it wasn't stopped up, and put the saw back together. I tried the pump just as it came on setting three but it would not oil so I set it to four but no change. Can anyone suggest what is going on? Before all this I never had any trouble. I don't know what else I could replace. If the pump is supposed to be primed can someone tell me how? Thank for any help.

I soaked the tube and solvent and blew through it. The air passed freely through it and it has no holes or tears so it is good. The drive gear fits snuggly into the clutch and you can see it turning. Do you know of a way to test these pumps?

Is the clutch worn? Could be that it's not engaging the drive gear when running? Just a WAG.

I ran the saw without the chain and bar and can see the drive gear turning. The clutch itself isn't very old and is pulling fine. As far as the tube, after soaking it, I blocked one end and blew through the other and there are no leaks so it is good. The stone filter is clean and I can blow through it freely. These are aftermarket pumps. I understand longevity may not be the same as a factory pump but they should certainly be working when they are new. Anybody had experience with an aftermarket pump?

I did try to prime the pump before installing. I will take everything apart and try again. The pump turns so fast when running I don't know if I will or should see any oil from the outlet.