If these are through-hole shaft mount encoders, Renco or Hengstler should be able to supply a substitute US Digital is cheaper made, but some use these.
A nicely made cheaper shaft style is made by Koyo.
Heidenhain extract a much higher encoder resolution than the native counts/rev with the sine wave output type, due to angular extraction between the two sine/cosine signals.
Al.
CNC, Mechatronics Integration and Custom Machine Design
“Logic will get you from A to B. Imagination will take you everywhere.”
Albert E.