Yes. The picture is exactly what I was talking about earlier. It looked like a missing screw to a novice.Glad you got it sorted. Just checked mine and was sending you this picture to confirm there is one in there. 3mm. Just deep. I have it uncovered and it was full of chips and seems fine uncovered. Tape will likely get oily and messy.
Also, I find that Kerosene works better than WD-40 when cleaning a whole machine. Stiff brush to apply, let it sit a bit and hard plastic scraper like for window tinting to scrape off the flats. Repeated brushing for things like the lead screw. I use a cup and sort of reclaim the kerosene until it is to full of gunk then get a fresh bit in the cup. Cleans well and won’t hurt the paint. Good luck.