aftermarket slave.cylinders

Anyone had an dramas with repco slaves.
Having engagement issues with the clutch has been checked and.told it's fine.but it locks me.out of second at 6300rpm and I did stupidly use a aftermarket slave as genuine was Japan order have since purchased correct slave
Just thought.I would see if anyone else has had this issue

Apparently it is the pedal feels ok just engagement issues sometimes it's fine otherbtimes no go