My Meyer E-60 lifts my blade just fine but won't hold it there. I just bought this unit used so I'm trying to get it up and running. It immediately drops the blade after releasing my 'up' switch. It is not a slow (leaking down) kind of drop either. It drops pretty quickly as if my 'A-valve' is stuck in the 'open' position. Is there any way to confirm this? I've ordered a new 'A-valve' and coil...any suggestions for testing and troubleshooting would be appreciated. Thanks.