ZBattery.com sells a PX27 equivalent, although the new cell is 6 volts compared with the original, which was 5.6 volts.
Glad to hear that you sorted out the problems. Most "problems" with the camera come from not knowing how to operate the camera.
Remember these tips:
- Never force the film advance if it stops mid-frame when you reach the end of the roll.
- The shutter must always be tensioned before you can collapse the lens.
- The lever on the aperture dial on the SE/TE models can lock into place, which allows the dial to spin freely.
- Never force anything on the Rollei 35 cameras. Ever.
- Take your time loading the film.
- Sometimes you have to jiggle the back a bit when replacing it.