Here is my solution for the battery compartment problem mentioned earlier. Shown in 10 images.
Hohner-B2A-Battery-Comptmt-0001: Remains oft he original plastic battery compartment. Parts have broken off, the lid is lost. A replacement part could not be found.
Hohner-B2A-Battery-Comptmt-0002: The deep cutout on the backisde oft he B2A body ist he original one, made to hold the plastic battery compartment. See the pre-amp circuit inside a PP3 battery shape housing.
Hohner-B2A-Battery-Comptmt-0003: The larger, about 1 mm deep cutout has been made by a friend of min using a milling cutter. It is the size of the new compartment cover.4 new holes (4 mm diameter) have been drilled. The upper left one already holds a threaded insert made of brass. The screws holding the new cover in place are M 2,5 x 10 mm.
Hohner-B2A-Battery-Comptmt-0004: Some oft he new parts: battery contact cable, brass threaded inserts, screws M 2,5 x 10 mm, self adhesive hook-and-loop stripes.
Hohner-B2A-Battery-Comptmt-0005: loop stripe is glued to the upper side wall, hook stripe is glued to one side of the the pre-amp circuit box.
Hohner-B2A-Battery-Comptmt-0006: Battery contact cable has been soldered to the corresponding wires of the circuit and isolated by tape.
Hohner-B2A-Battery-Comptmt-0007: Pieces of foam glued to the bottom an the lower side wall of the battery compartment as well as to one side of the circuit box, using double-sided adhesive tape. All four threaded inserts are in their places now.
Hohner-B2A-Battery-Comptmt-0008: Battery in it’s place, the new stainless steel cover shown above.
Hohner-B2A-Battery-Comptmt-0009: Piece of foam glued to the cover using double-sided adhesive tape, to make sure the battery will not move inside the compartment.
Hohner-B2A-Battery-Comptmt-0010: And that’s it. Great little instrument brought back to life. I love playing it.