Steenbeck editing tables were equiped with toothed belts that tend to disintegrate over time.
As a result, it is very often the case that one needs to replace these belts. Unfortunately, these belts were manufactured according to an standard that is now obsolete : “Synchroflex DR”, with a quarter-inch pitch and a 10mm width.

Steenbeck (now in Holland) stocks and sells these belts, and The Boston Connection does the same in the USA, and there might be other places that we don’t know.
Would one want to buy these belts in bulk, here is a source : Beltingonline but the minimum order is between 30 and 45 units.
Here is a diagram for the 16mm ST601 & ST 901 tables:

ST701 35mm tables usually require:
DR83 1 piece
DR 88 3 pieces
DR 79 1 piece