Those popular low compliance cartridges (Shelter, Denon,...) can take a long time to break in. I broke in my new Denon for the first 30 hours with the looked grooves on cardas record as well, and like Doug I did change the groove fairly often. Leaving the Denon with its spherical stylus in the groove longer than an hour resulted in damage to the groove not the stylus. The damage to the groove was pretty audible since the pink noise was much lower in frequency with the higher frequencies being damped.
Also is helps to alternate between lateral and vertical modulation grooves. And unlike Marakanetz I heard a clear difference after the break in. The high got much smoother and the highs went from unlistenable to extended and smooth. But then the Glider might be not as difficult to break in as the Denon. Certainly I would start playing with the VTA after the cartridge has been running for 50 hours.
Good luck and enjoy.
Rene
Also is helps to alternate between lateral and vertical modulation grooves. And unlike Marakanetz I heard a clear difference after the break in. The high got much smoother and the highs went from unlistenable to extended and smooth. But then the Glider might be not as difficult to break in as the Denon. Certainly I would start playing with the VTA after the cartridge has been running for 50 hours.
Good luck and enjoy.
Rene