manual transmission is hard to shift

be sure the pressure plate, throughout bearing, and slave cylinder are in position. In good shape, not leaking. Then Gravitiy bleed the master cylinder, by opening the slave cylinder bleeder valve, and let some of the fluid come out into a container. Keep the master cylinder full, many times these are hard to bleed all the air out after replacing. You can use a vaccum bleeder if avilable for faster results. After you get a good fluid flow close the bleeder valve, and bleed as you would brakes, pumping the pedal 10 times small all the way to the floor then hold have assistant open valve to release the air, close and repeat until no air bubbles come out.

Clean and flush master cylinder, bleed slave cylinder until clean fluid if the hard shifting still occurs, Replace the clutch slave cylinder