What I like to do on actuator setup is to first run the motor to the west limit switch stop but you need to make sure you don't bottom the inner tube out inside and break something. If you don't know exactly where your physical limit is on that inner tube, disconnect it from the dish and unscrew it or turn it out by hand enough to give you some room to work. Once you get comfortable with that, then manually run the actuator to the west limit switch where you will get an error on your receiver/dish mover. Once you are there, then turn the inner tube back in to make it as short as possible without running under the weather seal on the end or bottoming the inner tube inside the actuator. If it bottoms out then turn it back out a few turns to make sure it doesn't bind up while it's operating. Connect the actuator back up to the dish and loosen the clamp on the outer tube to move the dish (don't run the motor to do this!) to the lowest point west that you want to receive but make sure you go past that point enough to allow you some room to peak that satellite.
On mine I can get from 30 counts past 139W (electrical limit switch stop) all the way back to 40.5W and possibly beyond without anything binding up on both my SAMI and my Winegard dishes.
As far as signal getting weaker at the ends of travel, that could be something as simple as rotating the dish on the post and or, an elevation or declination adjustment being off.
So who set this dish up to begin with?