CM1981 says "They have great each support". Time to dial 'em up.

I do remember though on one of my units the crew that did the annual testing had to change the NTS speed values to set/check the OS valve. BUT...they failed to return and save the "normal" slowdown values which created trouble for me after they had left. Maybe something to look into.
Just a few thoughts as far as floor levels go; have you set them, saved them and then they've changed? Has the job got a new valve? Packing issues- i.e. tight? Both directions have changed? All floors change?