I just help replace a clutch for my friend car but now for some reason it wont into gear in 4th? It also some time pop out of gears in 4th? what could it be? Gear 1, 3 and 5 is fine but 2nd, 4th and R seem short or dont feel like its completely in gear.

Although 2nd works fine along with R. The only issue now is just 4th gear. Before we replace the old clutch when you shift it feel like its goes right into place but now 2nd and 4th just feel like its short or barely pass netural. What should we check?