I fitted my new, shiny tacho disc a few days ago. The surgery was annoyingly tricky: not fitting the disc, but removing the hub assembly. Actually, the fitting was easy - the reassembly was the problem, due to migration of the mounts of the suspension of the deck assembly, which fell off every time I tried to close the case. Steady hands, good light and thread to hold the springs in place temporarily all help. Children can be a distraction, but are useful for retrieving small parts which have fallen on the floor.
Reassembly completed, comparison of the speed stability of the 'gram 8000 with the old disc, the new disc & with my 8002 (which has a metal tacho disc as standard) was made by recording a 300Hz tone to CD: the 8002 & rebuilt 8000 are equally stable, the difference with the old, cracked celluloid disc is obvious even listening in the car when driving!
"Dillen" has indeed 'cracked it' & deserves our thanks.
Now I only have to sort out the arm on the 8000, which lifts off unpredictably, then I can decide whether I prefer the 20-series cartridges or the MMCs!
Adam Kimberley.