[John22j]

Is the chain clean and well lubed?
Axle straight (chain adjusters even on both sides)?
Can you eyeball it and make sure the sprokets are straight as well.

does it "pop" when you roll it or does it move freely just gets tight?
will it do this if you spin it with the rear wheel off the ground

When you say "roll it a bit" is that with the bike standing free or with someone on it?

If you have pictures that's a bonus, but we should be able to trouble shoot it without them.