Pressuretrol / cut in-off accuracy

Dave_4

I just cleaned out a very clogged pressuretrol pigtail on my one-pipe steam system (it wasn't cutting in at all). It's a Burnham boiler, installed in ~1998, with a Honeywell PA404A1009 pressuretrol. The pressuretrol is set to 0.5 cut-in with a 1 psi positive differential, so I should see it cycling up to ~1.5psi, and then back to ~0.5psi, right? Watching the pressure gauge, I'm seeing it cut-in at ~1.25psi, and cut-out at ~2psi. The pressure gauge is mounted on a separate knock-out from the pigtail.

Is this normal to see such a difference from what I've set it to (maybe 1/2 to 3/4 psi off)? I'm not sure how accurate the pressuretrol settings are supposed to be. Also, I've never really paid too much attention to the high/low cutoff points before now, so I have no idea what it was working like in the past (although the pigtail was *SO* clogged I'm not sure what I would have made of the comparison). When the thermostat is calling for heat, the boiler is on ~3min, and off ~30sec. Does this sound correct?

Thanks in advance...