New to wine making and I will be pressing by first batch of Cab in the coming week. In getting my press cleaned off I noticed the main vertical "screw" a bit wobbly, but not too much. I looked under it an noticed a large nut which appeared tight, however the whole shaft spins in its sleeve. Is this normal? I can't help thinking that their should be a seal at the bottom of the shaft to keep the juice from leaking out of it and under the press. Thanks in advance.