Skimmer crapped out....where to start troubleshooting

[Coralgurl]

Yesterday morning my skimmer started making a horrible rattling noise. I thought maybe a snail crawled in somehow and jammed things up so turned it off. Plugged it back in and wasn't so lucky. Problem is, I can't get it out of the sump without completely draining the sump and pushing it out the end. Ya ya no need for comments on this

I removed the bubble plate and tried feeling around, pretty useless. So the plan is to drain it tomorrow night and get it out. I just don't know what to look for other than the obvious...snail or something.

The manual has no instructions for trouble shooting so can someone point me in the right direction? I dont want to pull everything apart and not know what to do next or look for. Thankfully if it's the pump it's got a 3 year warranty......