For the last two weeks I have been working against degrading operational characteristics of my good old dependable Probotix V90 Fireball. It started with non-circular rings cut out of 1/8" aircraft plywood. It has now gotten so bad that I can't cut concentric circles, let alone hold tolerances to within acceptable levels.
I'm using Vectric Cut 2D CAM and Planet CNC USB controller. The router is a Ridgid R2401. I checked for backlash, loose rods and guides, and TIR on the router. Everything seems to be fine. I have changed cutting speeds, feed rates, cutters, and even stock hold-down methods.
I'm using Haas, Hurco, and Bridgeport milling machines at work, so it's not exactly foreign territory. But this problem has me bamboozled.
Any ideas (besides getting another machine)?