BBC GT13D Speed Adjusting Device

We are in the process of replacing a speed adjusting device for BBC GT13D model. In the process of examining the different possibilities we could not locate any because the model is obsolete, we need more information in this regard to support our searching.

1. Does anyone has any reference of upgrading the system or that can supply?

2. What are the other Control system available in market that can matched perfectly with the operations?