Cleaning and Lubricating Stiff Replacement-Window Tracks

A few of my replacement windows have become harder to operate, and I’m trying to determine whether they just need cleaning and lubrication or whether the hardware is starting to fail.

The affected windows are vinyl double-hung units. One sash feels stiff through most of its travel, another makes a light scraping noise near the bottom, and one moves unevenly even though it still opens and closes. I haven’t noticed broken weatherstripping or visible damage to the frame. So far, I’ve only vacuumed loose dirt from the tracks and wiped them with a damp cloth. I haven’t applied lubricant yet.

My tentative maintenance sequence is:

1. Open the sash and vacuum the tracks, corners, and weep areas.
2. Wipe away stuck-on grime with mild soapy water, then let the surfaces dry completely.
3. Check for grit, paint, bent track sections, loose screws, or anything rubbing the weatherstripping.
4. Apply a small amount of lubricant specifically labeled for vinyl-window tracks or the manufacturer’s hardware, avoiding oily sprays that could attract dust.
5. Operate the sash several times and wipe away excess lubricant.

I’m unsure how much of the mechanism should be lubricated. I don’t want to spray into the balance system, contaminate the weatherstripping, or damage the finish. For anyone who has maintained replacement windows, which parts did you lubricate, and what cleaner or lubricant worked without making the tracks dirtier?

Also, what symptoms made you stop cleaning and call for service? I’m particularly interested in distinguishing ordinary dirty rollers or tracks from a worn roller, damaged balance, loose fastener, or another hardware problem.