Difficulty of engaing first gear

I'm finally having a chance to put a few miles on my recently restored 72 Commando.
I bought the bike then did the restoration immediately as it wasn't in running condition.

Normal shifting up through gears smooth, coming to a stop and down shifting to first works fine and finding neutral easy.
However after I've shifted into neutral and try for first gear it usually won't engage. No funny noises, just doesn't seem to go far enough.
If I roll the bike back a bit so the gears are turning it will usually then engage first ok.

Any ideas on what is going on and what I can try to solve it.

Thanks in advance

Bob

Your gear selector camplate could be worn, and/or your shifting engagement linkage could be wearing a bit.

Hi RX,
I too experience the same thing from time to time. Usually I can tell by the feel if the neutral to first shift engaged fully, if not I hold a little up pressure on the shifter as I let the clutch lever out and it clicks the rest of the way in. It could be caused by worn components as grandpaul suggested, but I suspect it has more to do with clutch drag than anything else.
Since I converted to primary belt drive (dry clutch) it is much less of an issue.
GB

I'm going to come in at different angle. It maybe the ratchet spring not moving the gearshift paul onto the ratchet plate properly. I & a friend had a problem when we renewed ours a few years ago, it would change up alright, but now & again it would not shift down. We put our original ones back in again.
Waffle over.