I NEED YOUR HELP!...PLEASE!!
I'm a bit confused (I think) on what is going on with the cover (shown below) regarding "POSTAGE DUE RATES & USAGES" as it applies to "BULK MAILINGS", "PRECANCEL USAGE" and "RETURN POSTAGE GUARANTEED", " under "SEC 34.66 P.L. & R".

Here are my questions (thoughts) about this cover:
1. Am I correct: Is the "Postage Due Service Fee" for "RETURN POSTAGE GUARANTEE" endorsement on 1˘ Bulk Mail, under PL&R Sec 34.66, a 1˝˘ FEE on 1˘, during this period (1950s)?
2. The face of this cover is marked,
"8" (diagonally) below the upper left corner card, indicating an "8˘ deficiency".
3. The cover was mailed under 3rd Class Bulk Permit by a New York City Bulk Mail Permit & Precancel Permit Holder (a Mail Order Company), at the upper west side, Columbus Circle, New York 23, N.Y., post office (now 10023).
The cover arrived at the Del Aire branch, Los Angeles 45, CA., post office for delivery. There the cover was stamped with two (2) red-violet auxiliary handstamps, including: "RETURN TO SENDER" and 'REASON FOR NON-DELIVERY". The cover was returned to New York 23, N.Y.
The cover returned to the Columbus Circle NYC (23) Post Office was then handled by the Clerk that handles Permit and Deposit Accounts (i.e.: All Permits, Postage Meters, Box Rents, Mail Deficiency, Deposits, etc.). There he/she marked the cover with the
"8" and placed 8˘ postage due on the cover; 5˘ (Sc# J83a) plus a 3˘ (Sc# J82a) which is now covered.
Later, the Postage Due Deficiency was changed. The 3˘ Due (Sc# J82a) was covered (at bottom) with a second 5˘ Due (Sc# J83a), correcting the Deficiency Due to 10˘!

Having been in the mail-order business for over 30 years I think this is what happened:
Most Mail Order Firms have BRE/BRM (Bulk Reply Envelope with a required Deposit Account.
I think HELEN PERL was a BRE/BRM Permit Holder. They had "returned" mail accumulated over several days. The Permit Postal Clerk had computed one charge, then having received or found additional "returned-to-sender" pieces (6 pcs @ 1˝˘-per-piece) changed the charges to the Permit holder (PERL) to 9˘,
plus the required "1˘ Daily Account Maintenance Fee" to equal 10˘ shown.
Of course, there may be an entirely different explanation as to "What", "Why", and "How" 8˘ became 10˘, but this is why I need your help. Am I correct? Or, what is the explanation for a 10˘ deficiency charge on this cover?!?
Here is a 1 x 1 HELEN PERL COMPANY space ad. HELEN PERL was a mail order company that sold medical aids to Breast Cancer survivors.

Thanks in advance for your review and help on this cover.
Hal
P.S. To everyone: may you and your families stay healthy and safe during the COVID-19 outbreak!