Yeah, that one looks like it needs to go back for a refund. Pretty bad. I've had to send a few back. Not a big deal these days, ebay stands behind their buyer protection program.
You probably already know this, but here's the basic plan for a smooth return;
1) Make all communication with the seller via ebay PM's. Avoid email. Insist on it.
2) Stay cool, stay polite with the seller even if he becomes hostile with you. Try to work out a return/refund with the seller. (he probably won't agree, but that's actually a good thing)
3) Get his contact info from ebay. Phone the seller and politely discuss the issues with the bass, and that you need to return it for a full refund. Ebay wants you to do all this preliminary legwork yourself before they take over.
4) Don't worry about getting your return shipping costs back. You will, even if Paypal pays for it separately. It's guaranteed.
5) It doesn't matter if the seller refuses your demand. As long as you've done the proper comms, ebay and Paypal will cover the refund.
6) When you ship it back, make sure a signature is required upon delivery.
7) Once your claim is escalated to a dispute, ebay takes over completely and you won't have to communicate with the seller any further.
8) Put the seller on your ebay 'blocked bidder' list.
Easy-peasy. Good luck.