I got a second hand V. MP10 that I'm going to replace the wet side, because the rotor went unbalance due to rotor opening on the bottom, I know this is been used, don't know for how many time, even not thinking for now to claim any guarantee because I don't have purchase receipt, also I was so lucky that the member who sold to me agree with no problem at all to refund me so I could get a new wet side, something that really never expect but didn't expect to put the pump in use and not make it work, might be because pump was in storage, well, just want to know if this could be an issue to deal with everytime you need to replace wet sides, or is a normal wear. Thank you.