Glue on felt on bottom of guide rails with felt glue. We used Roo Glue here. Trim felt and cut open screw holes. Without cutting the screw holes open, the felt will twist, move or loose it's position when driving screws in later.
Use a soldering iron to ream the damper wire holes before installation. With the wires going to be installed, try and make sure every hole is loose or not binding. This will be hard to do under/through strings after rail is fastened into piano.
Locate treble guide rail with felt mute/wedges under strings, fat side facing back of piano. Pull the wedges towards front of piano to fasten the rail. Make sure it is tight. Check that every damper wire hole is in between unisons, so the damper wire clears or not touching strings on left and right. The homemade jig makes sure that the testing damper wire is 90 degrees to the strings.
At one end of the rail, use felt mutes to open up space between strings for screw installation. Use a transfer punch to make a mark and help centering the drill bit. The punch is at same size with screw hole. Drill for screw holes.
Wax the screw and install. Check again for the position of the whole rail before carrying on. Make sure all holes are still at the correct positions. The first drilling and screw installation may cause the rail to move a little.
Mark, drill, and install the screw on the left end of treble guide rail. Now that the rail location is locked, go on to install the screws in the middle.
Move on to the bass guide rail. The process is the same. If the bass rail needs to move to the right but already butt against the treble rail, sand the right side a bit to fit. Always check rail/wire hole location with the wire-to-be-used, making sure the wire won't hit strings and cause buzz.
Finally, check that all screws are tight. If loose, buzz may occur while piano is being played. This part of work takes a lot of detailed attention but very necessary, in deed. Thanks to my mentors and boss to teach me every little step in this industry.