Cleaning a Sprial Balance

I recently cleaned the spiral balances on my 20-year-old double-hung windows where only the lower pane tilts inward. I wiped the twist rods with mineral spirits and put a few drops of oil at the top of the spiral balances (the piece of plastic on the twist rod appears to be orange in color). After raising and lowering the windows a few times to work in the oil, they now slide up and down in the sill very easily. However, if I close the windows completely overnight, in the morning there is resistance when opening them, followed by a loud twang (that sounds like a spring releasing), then the windows move freely in either direction. If the windows are left in an intermediate position overnight, they slide in either direction easily and quietly in the morning. Is there a way to clean or lubricate part of the spiral balances so the windows do not

Paul, thank you.
The "sticking" is something that started happening over the last few years. Some windows stick (those used more frequently), some do not (those used less frequently).
When it stops raining over the next day or two I'll try moving the balances on one window and let you know if it that works.
Nick