That gold colored can is in fact the "stop" per say to adjust how much the slide comes in. The nut next to it just secures the can. The outer 2 nuts on the thread adjust how much the slide goes out. You also have the drive shaft that runs from the motor end rail to the slave end rail. I'm guessing the motor end is the one with the adjustment piece. Not saying it's right, but I have disconnected the drive shaft between rails, rotated one end to "even" the slide out, then reconnected. Did this on an above floor lippert system and it fixed the problem of one end being in / out more than the other.
John and Rebecca Dickson
Emma-7 / Little John-5 / Iva-1
Full Timing Again, Rev B
2013 Ford F-350 Lariat CC LB PSD
2015 SOB TT - With OC's Awning Poles (#8)
At least in Heaven, RVs will be perfect, and I won't have to keep fixing them.