These screws should be epoxied. Release the focus brake and turn the drive by hand. The drive should turn smoothly. Note any damaged bellows. Loosen bellows hose clamps.
Slide bellows out of the way to inspect lead screws.
The lead screws should be clean, rust-free, and covered with a film of grease. Wipe off the screws with clean, dry rags. Note any problems. Pump grease into the lead screw bearings until clean grease comes out through the seals. Replace any damaged hose clamps.