Monitor drag vs. Ergdata drag vs. logbook drag

[TDinBristol]

Wondering if anyone can advise:
I use a Model C I got from someone who had only used a few times (i.e., in pristine condition), and retrofitted it with both the "quiet kit" (chain, cog, bearings) and with a PM5 monitor. It's been a pleasure to use, but I've found one odd thing - the drag factor that I set on the machine, and which I see on Ergdata as I row, is frequently quite different than the drag factor that shows up when I upload it to logbook.
For example, a 150 on the machine came out as 172 on the logbook; a 115 came out as 131.
I don't know if this is fixable, but my more important question is this - the drag I set on the machine/PM5 is the "true" drag, correct?
Thanks for any help.

[msongy]

Wondering if anyone can advise:
I use a Model C I got from someone who had only used a few times (i.e., in pristine condition), and retrofitted it with both the "quiet kit" (chain, cog, bearings) and with a PM5 monitor. It's been a pleasure to use, but I've found one odd thing - the drag factor that I set on the machine, and which I see on Ergdata as I row, is frequently quite different than the drag factor that shows up when I upload it to logbook.
For example, a 150 on the machine came out as 172 on the logbook; a 115 came out as 131.
I don't know if this is fixable, but my more important question is this - the drag I set on the machine/PM5 is the "true" drag, correct?
Thanks for any help.

In your PM5 setings, are you sure it's set to Model C? And might firmware version have any impact? And if you display drag factor on the PM itself, what does it read compared to ErgData and the log?

[Citroen]

Clean the flywheel magnets (and check they're all in place and not rattling round the bottom of the fan cage).
Clean the pickup.

[TDinBristol]

Thanks - I bought the PM5 in the fall as a "Model C retrofit," so I assumed software was matched, but I'll definitely check. And will clean the pickup and check the magnets.
I want to be able to jump on a machine at the gym and set it knowing I'm using the same drag I would on the home machine; it sounds as if the disconnect between numbers is not a common experience for others.
Again, thanks.

[Citroen]

There may be some value in picking up the phone and calling Concept2 on their toll-free number.