[roger_e]

I have some used INA linear bearing KWSE 25....the block kind, that ride on a profiled rail.

Anybody familiar with replacing the ball bearings inside?

[hmotion]

It's not worth trying. The carriages can be replaced for $55 ea and the rail for $95/meter. Your in this deep, do it right.

[loka]

linear bearings are just like radial bearings.
do you replace only balls in radial bearings? no you wouldn't because if balls are worn out, raceway where balls run will be worn out also.
just like radial bearing, linear bearings have inner and outer race. outer race is the block, and inner race is the rail/shaft.
so if block is worn, most likely the rail is worn too, or will soon. its a good idea to change both because running good block on worn rail is not only give u unsmooth motion, it will worn out the block quick also.

changing balls in the block is not easy because you don't know what size ball is in there. and size here means micron increments of say 1/8" ball to have proper fit/clearance when assembled. heavy duty blocks have multiple ball circulations and each circulation may have different increments of balls.