if its me i'll buy a new 1GSps DSO unit and dont have to bother with the "missing knob" issue.
Well, the thing is that the new 1GSps DSO you can get for the same price would be a two-channel low bandwith Hantek, Atten, Siglent or Owon with a tiny screen, has a good chance to come with a shared ADC hybrid where 1GSps is only usable with one or even only 'half' a channel, shoddy software (if there's anything at all), no proper LabView drivers, buggy firmware, simple triggers capabilities, and not even half of the advanced signal analysis capabilities of these LeCroy scopes.
And chances are good that the remaining life of a 13 year old Waverunner is longer than the average lifetime of most of these China scopes.
I think I'd rather deal with replacing a few standard D-type plastics knobs.