Here is what I do.
Using a tiny drill bit, or ice pick, or awl, or Treadle belt pliers make a hole a little over 1/8" from the end of a belt.
Feed the belt through the machine and table as if you were going to use it.
Overlap the ends and pull snug (NOT super tight, just remove all the slack)
mark exactly where the cut end meets.
Now remove the belt
cut where marked and use the above to make the hole the same as the other end.
Re-feed it through the machine and table, but leave it off the bottom wheel.
IF USING SHRINK TUBE- slip shrink tubing over one end far enough to expose the stitch/staple hole
stitch the two ends together (or install staple)
IF USING SHRINK TUBE- slide tubing over joint
IF USING SHRINK TUBE-heat gently until it is "shrunk"
IF USING SHRINK TUBE-allow to cool
place over wheels as normal and treadle away.