Your leech is 'hooked up' to weather; leech is too tight from either too much mainsheet pressure (or vang pressure); or more probably, the sail isnt sufficiently 'raised' (not enough mainsail halyard tension after raising). Could also be your reefing clew lines are too tight.
My suspicion is insufficient halyard tension (or insufficient cunningham tension). The Helms 25 has a mainsail luff dimension of approx. 25 ft. so when 'raising' the main, get it 'up' and then add an additional 2 to 2-1/2" of luff stretch via extra halyard, etc. tension so that the sail takes on the 'designed' dimensions that the sailmaker intended. Once you get this proper luff/boltrope tension, put marks on the halyard and a corresponding mark on the mast so when you 'raise' and 'stretch' you be at close to proper tension and 'stretched out
' luff dimension every time. You have to 'stretch out' the luff on dacron sails made with luff 'boltropes' ... otherwise they will set with a 'hooked up' leech and will be 'draft aft' --- only good for extreme 'weather helm' and very aggressive heeling ;-).
The tack angle (the angle that the top of the boom makes with the mast when the sail is 'properly
raised') for a Helms 25 main is 88°
Here's how to properly raise a 'boltroped' dacron mainsail: How to properly RAISE a woven dacron mainsail - SailboatOwners.com
The H25 is fairly quick and lightweight boat so a more forward draft position and more 'rounded' luff shape (a 'speed shape') from higher halyard tension will be of benefit, especially when sailing 'fast'. The 'rounded' shape of the luff section will be 'more forgiving' in 'variable wind and boat speeds' .... use extra outhaul tension when doing this to keep the 'amount' of draft a bit 'minimized'.
When you get the luff tension correct, those diagonal small creases ('girts') radiating from the clew to the middle of the luff will probably disappear.
You also need
to 'lubricate' your mast track.