You're welcome for the chart—even though it is based on my photo observations and memory rather than definitive data.
Hopefully, someone who has all three can verify or correct it.
Anyway, regarding your pn's performance issue, I located an archived link that contains some possibilities:
https://www.vacuumland.org/cgi-bin/TD/TD-VIEWTHREAD.cgi?32816
I wonder, too, if you have an aftermarket brush roll that has bristles slightly too long. There's a shut-off mechanism that engages with too much spin resistance—which could also be the belt as you mentioned.
