Sterilemax Autoclave not Draining

The unit gets up to temperature and pressure fine and is able to complete the sterilization exposure phase. However, following venting, the pressure remain high and once 2 psi is reached the unit does not drain and it takes a long time for the venting cycle to complete. When I open the chamber there is about 100 mL of water remaining in the bottom. I've watched teh drain and it definitely does not recirculate back to the reservoir. There is a solenoid that opens the drain which may be the culprit, but because the pressure remains high I'm wondering if there is a vent issues and the drain solenoid never get triggered? Has anyone else seen something simila? Any suggestions?

Thanks!