Sounds as if something is not seated correctly, or you have binding due to a poorly machined part. I’d do a full strip and thorough clean, checking all parts for burrs. When you re-assemble, the switch contact should screw all the way in. I see people loosen this off - you shouldn’t need to do that. If after all this you still have a problem come back as there are other potential fixes with the use of o-rings.