Originally Posted by
Hondo6
I presume the OP has verified that his BB cups are Raleigh-proprietary 26TPI cups;
His serial starts with W; the probability of 26tpi is close to zero.
If there is any doubt, a known 24tpi cup will mesh with another 24 tpi (as it should), but will rock back-and-forth when a mesh with 26 tpi is attempted.