If you look at the part numbers of the individual parts of the TB knob assembly, most of them are identical with other scopes of the series, e.g. the 1740A, 1741A, etc. In particular, is true for the two knobs (Main TB and Delayed TB). Since you still have the dial with the delayed TIME/DIV decal (the 1740A, etc., have different TB settings) as well as the two shaft assemblies, getting the two knobs from a 1740A or similar might be enough.
I have an old 1740A parts donor sitting in the basement. However, I don't know if its TB knobs are still okay, and whether shipping from Germany would be economical.