Have had success with a CANPA hatch on a 27 dealing with both issues.This copied from a response made on YBW.May not be relevant to your boat.
The 'plastic' hinge pins will pull out if you insert a knife edge underneath the head of each.https://picasaweb.google...link#6089072406456086306
I found that the hatch distorts with age and no longer lies in the precise plane of the frame so leaving a small gap when the hatch is closed and touching the frame.Sorted by removing the seal and rebedding it on a bead of sikaflex.Close the hatch onto a coin or thick washer at the leading edge until the sikaflex has gone off.Then remove coin.The seal will now follow the exact line of the frame and will compress all the way round the seat.Now snug.
As has been said you can work on the seal without removing the hinges.I also had a leak twixt glass and frame.Resolved by cutting out the old perimeter sealant with a scalpel (used for graphics) cleaning out groove thoroughly and repointing with black sikaflex.Not as good as rebedding but works and fairly easy to do,with the right glasses !
The sealant can be trimmed after it's gone off.
If this helps.
Peter
An ironic interchange.I see from YBW that it's a Houdini!