As Roger stated, the best way to glue the window pull blocks (Plex or glass) to the glass pane is auto mirror adhesive. I've tried two-part epoxy--- it does not last as long.
Lubing the tracks on a GB is a tricky thing. Just about anything you put in there will attract and hold dirt which in turn accelerates the deterioration of the felt weatherstripping. UV also hastens the deterioration of the weatherstripping which is why we put our exterior window covers on the opening windows whenever we are not using the boat. These help protect the weatherstripping from UV as well as reduce the amount of dirt that ends up in the tracks.
The best way to keep the windows sliding easily is to keep the lower track clean.
It is very important to periodically clear out the track drain holes that are (or should be) at the rear of each lower section of track. This is not the same as the drain that drains the inside sill of moisture. This is a hole in the track itself that drains through a small hole in the bottom of the frame (at least on the older boats). These holes are easily plugged with dirt and fibers from the weatherstripping. When they get plugged up, the tracks won't drain and water stays in them for a long time, further deteriorating the weatherstripping. We use a short length of coat hanger wire to clean the drain holes.
We have one large sliding pane on the boat that does not slide as easily as the others. It's a replacement pane and we rebuilt the frame so I suspect there is a slight alignment issue. When it decides to stick we put a couple of drops of Lemon Joy in the lower track and slide the glass back and forth a few times. This does the trick for awhile until rain and washing the boat eventually removes the soap. Our boat is old enough that the sliding panes are on the outside. Newer GBs have the sliding panes on the inside.
I don't like doing this because the soap traps dirt but for now it's our only choice. Eventually when we have more time we'll rebuild this window again and solve the problem properly. Rebuilding the windows on a fiberglass GB, at least an older one, is dead easy, but it does take time. New stainless track is available locally at Fisheries Supply and we generally keep three or four eight-foot sections in the garage at home for window projects that might come up.
We also have a number of precut 1/4" Plexiglas "windows" that we screw over the hole in the side of the cabin when we have a window out of the boat for a total overhaul of the frame. That way we can keep using the boat regardless of the weather while we overhaul the frame at our leisure at home, have new glass panes made, etc.
Over the last 17 years we've rebuilt most of the 21 windows in our boat to various degrees, some with new glass, track and completely overhauled frames, others with just overhauled frames, and so forth.
