Too much clearance between the rotor, endplates and or housing can result in air loss. Measure the rotor to endplate and rotor to housing clearances to confirm that they are an NFPA compliant 0.0079 inches. If the clearance is larger than this, it might be time to replace your rotor, rotary valve, or have it sent back to ACS for a repair or evaluation. Make sure to stick to a maintenance schedule and check your clearances at least every three months.