The latest word from Canon Germany is that USM motors and electrical parts are no longer available for all of the pre-1999 Super Telephoto Lenses (the non-IS models), and therefore, these lenses have been removed from Canon Germany CPS service.
These models include the 200 f/1.8, 300 f/2.8, 400 f/2.8, 400 f/2.8 II, 500 f/4.5 and 600 f/4.0. (thanks Ralf)
Ralf thinks we will see some new, larger lens mugs coming in the near future.