Low Suction on 10 AMP Power Smith PAVC-102 Ash Vac?

Hello
To properly analyze the issue I needed to get a baseline on a brand new ash vac and I used the same commercial hose.
Central vacuum installers use a vacuum guage that measures suction power in inches of water lift. A good central vacuum measures 90 on the Guage.
So I took out a new pacv-102 from the box and it measures 60. Very good suction from a small portable unit. In fact my larger shop vac that is not clean measures 60 also.
Now I measured my older PAVC-102 that I cleaned and blew out the bag and secondary filter so it is as clean as possible and measured a minimal 20 on the Guage.
So then I removed the secondary filter that I blew out with the compressor and put the cage back on to prevent the filter bag from being sucked into the motor. Then I measured 60 Ah Ha!
Has anyone seen where you can easily buy these secondary filters?
Looks like there is a number to call for service & support?

Pic 1 - Brand new PAVC-102 measuring 60
Pic 2 - my used cleaner PAVC-102 measures 20 ??
Pic 3 - my used PAV-102 with secondary filter removed
Pic 4&5 - The secondary filter is clogged!
Pic 6 - Service & Support phone number, website and email.

 

I put in A new secondary filter and it is back up to 60 now!
Did you check the suction on your ash vac lately?