I'm wondering if any of you recognize the following issue:

Lately I've to do quite a bit more efforts to control the spinaker sheet. It slips thru my gloves, and when sailing the kite I have a lot of trouble to sheet it in a few inches. The pulling force is very high in my opinion. However I cannot remember that it was always like that. Maybe I need some more training, but I wonder what else can be the cause. I have no problems with the mainsheet whatsoever, it only occurs on the spinaker sheet. Especially when sailing a longer track it's difficult to hold it. (due to the force, or due to bad grip?)

The gloves I use, I use already for a longer time, and seems ok to me. The sheet is more or less original I think (Nacra Inter 18) Although we had two, but with the first set up it ran a bit more difficult thru the blocks (we could barely get it in). To make it run more smoothly we shifted over to the slightly thinner version sheet and larger blocks on the beam. Can this be the reason?

We rig the sheet like it should from my hand to a block on the beem, to a block on the side which has a break included.

Any ideas?