I just changed sprockets/chain and I noticed that it�s difficult to change gears.
At traffic lights I�m struggling to get in neutral.

I checked the engine oil and it was fine. Any ideas?

check the chains tension,and alignment.

is your clutch and cable adjustment okay?

Sorry it took a while to respond but I finally sorted that out.

Tried a few things and in the end, Destiny was correct. The clutch arm right above the gearbox needed adjusting. 👍

You might have damaged the gearbox while taking off the front sprocket