09 Big Bear 400 IRS wont move..

Ok so I’m looking at a 09 Big Bear 400 IRS for sale that will not move. Guy tells me he rebuild motor, with new crank, piston and gaskets. He put bike back together and now the bike will not move. He says it shifts up and down but not moving? Any suggestions?? He’s asking less than 2k for bike.

Thanks,
Todd