Jose:
By your description that your sheet leads forward to the mast then routes back to the cockpit, it seems that you have mid-boom sheeting -- rather than the cockpit traveler sheeting as Ed has pictured?
If so, this is the set-up on the 1980-82 Cherubini Hunter 36 (my boat).
The attached pictures show how I modified my boat towards the outcome you are looking for. I can go either hand sheeting or with the winch if I want more tension. 99% of the time, I don't bother with the winch. So the rope clutch stays open. If I want to sheet close to the center-line when the wind is blowing, I pinch into the wind a bit until the sail and boom luff and then pull. If I want to use the winch, then I close the rope clutch, remove the sheet from the cam cleat, wrap it around the winch, tension, unwind the sheet from the winch, put it back into the cam cleat and lead the line back to the helm. Snapping the sheet out to the the cam cleat when under tension can take a few aggressive tries.
I did change out my fiddle block (also falling apart when I bought the boat) for others and more of them to add more purchase. If you don't increase the purchase, then manually tensioning the sheet becomes hard when the wind picks up.
Finally in the pic of my pedestal, note the eye-bolt that I mounted on the pedestal guard. I flop my sheet over this so the sheet is always at hand.
rardi