A 1000 line quadrature encoder such as you have puts out 4000 lines per rev.
The quadrature signal produced by incremental encoders has 4 state changes per quadrature cycle. A 500 CPR encoder has 500 cycles (2000 quadrature states) per revolution. x1 decoding means that the external electronics counts only state per quadrature cycle, so there will be500 counts per revolution. x2 counts two states per quadrature cycle (1000 counts per revolution). x4 counts every quadrature state (2000 counts per revolution
You mentioned you only used the A and B channels? and not the complimentary channels, so at that you would have 2000 per rev.
Of course it depends on how the MPU is set to read the inputs from the encoder.
LOL.....I dont know how it works at all.
What is the part number for the new encoders?
Happy New Years