Recently wanted to lighten the pull on a used 78 I picked up. Figured out that, with the knife about 1/4 the way open, you could wedge something between the blade tang and backspring and then, holding that in place move the blade towards the half stop position and the wedge would force the spring out further than normal by being between the tang and backspring. It's a tricky thing to do...a third hand would really help, but it can be done. I successfully lightened the pull on a 78 from an 8 or 9 to a 6 or 7. So much more friendly now and absolutely zero harm done. Not to say there isn't risk, I'm sure you could go too far or break a spring, but it worked great for me.
It helped that I scored the knife at a great price off the forum so had things gone bad it wouldn't have been quite as painful...but stilly really happy it turned out well.
