We have been using Scotch Tape (This might be called TESA in Europe). Depending
on how clean a splice you need, you can arrange the two ends of the tape with
their back side on the scotch tape and trim off the remaining scotch tape. A
diagonal cut is best. The alignment is a little tricky, but it gives you a
splice that will work for a while.... We even fixed broken VHS tapes this
way.....

In the past we had a rig and some special tape..... long gone....

Otmar