Finally figured out why my shutter curtain timing was always off by a hair

I was working on a Pentax K1000 from a local shop, and the second curtain kept lagging just enough to overexpose the right edge. For months I'd been adjusting the spring tension, but it never stuck. The tip-off was a tiny bit of old, sticky grease on the curtain roller axle that I only saw under my bench light at a certain angle. Cleaned that off with some lighter fluid and a cotton swab, and the timing snapped right into place. Anyone else miss a simple cleaning step that turned out to be the whole problem?