I used to have a pair of HB2Rs purchased in 1986, these may be the same as
yours they did not have anything in the port.

Steve

I too had a pair of HB2's of original origin and these did not have any
restive port loading from memory. I never thought the ports needed any
adjustment in that manner unlike a pair of Epos ES14's that my mate aquired
at some later date.

Steve