seeking parts for dia-compe cantilever

Trying to get an old mtn bike in working order for a friend.

The front cantilever brake is missing the "spring block" which is a
washer/bushing with a hole for the spring allowing finer adjustment of
spring tension. Since it is missing, the arm cannot be fully tightened
on to the boss on the fork.

The model is dia-compe XCE. If you have some parts or a a complete brake
(for cheap), please email me at yahoo.com, the userid is gfbhwo.

Thanks,

Gareth