Sump Pump running but not pumping water
I'm having an issue with my 3 year old Barracuda sump pump running, but not emptying out the sump basin.
The pump has been running properly every couple of hours for the past 3 or 4 days (first time it has run since the weather started to warm up), but last night my wife woke me to tell me that the pump was running, but wasn't shutting off.
I checked the discharge PVC pipe outside between the house and the ground, and it was clear of water or ice. To eliminate any potential blockage in the piping underground, I left the pipe disconnected so that water should just discharge out onto the ground.
This morning I bailed out the basin, and removed the pump. I checked the pump inlet for debris - it had a minute amount of crud on the filter which I removed. I also cleaned out the built-in airlock device with a paper clip. I reinstalled the pump and poured a bucket of clean water into the basin. The pump started up, but because I hadn't re-tightened one of the clamps enough where the pump connects to the check valve, it sprang a small leak - so I assume that the pump itself is working as it should? If that's the case, the only other problems I can think of are a blockage in the copper piping between the check valve and the outside of the house, or the check valve itself? I'm pretty much a novice, so I have no idea if a check valve can go bad to the point where it doesn't allow water to flow out of it?
Anyone have any insight?
Thanks in advance.