When gear is hard to shift, turn off the engine and then shift. If it shifts smoothly, it's probably warped flywheel, or some pressure plate or clutch plate issue. Did you get the flywheel polished? If not, that's the culprit. Sometimes tooling machines are mis aligned and they cause slightly uneven tooling of flywheel or some mechanics even don't tool the flywheel at the time of clutch and pressure plate replacement (especially if it's replaced before it's worn out).
I suspect warped flywheel, with confidence. It may not be tooled at all or incorrectly tooled.
Gears shifting gets smooth with engine turned off?
If it's gear issue, then it will stay hard even with engine turned off.
