>This box has one PN-RSTBA DTMF receiver card,
>located in PIM 1 (the whole thing has 2 PIMS).

>Does this card handle DTMF for the entire box?

DTMF recievers are shared for all system.

Check that ports assigned in CM10.
Try delete card CM10>xxxx:CCC and write back.
Reset PBX