Balancer Spring Strength

We bought a 10 yo house about 2 years ago. We have numerous single hung windows and almost all are very hard to open or close. We had a balancer break on one and had a local window company replace the balancers on that window. It is much easier to open and close now. I decided to try to change the balancers on two of the other windows to see how that would go before tackling all of them. I purchased (4)S380-31 31" Series 380 Channel Balance Option 3050 (Window Weight ~30#) and installed them. The windows operate better but are still a bit stiff. They are harder to close than open. I was thinking an option 3040 might make them easier to open and close. What do you think?

I was using an older bathroom scale and it looked pretty close to 30#. All the windows seem to have quite a bit of friction. I have cleaned them and lubed them with silicone spray. The ones I changed the balances on are better but still noticeably harder to close than open so I thought a slightly weaker spring might do the trick. I couldn't find any markings on the old ones to indicate stamp option.