Slide problem

[six point]

We have an Alpenlite spyglass 29 ft w/living room slide.
It is leaving black marks on the floor and is actually digging in to the floor on the front , the fridge is on this end.
When closing it picks up at the end of travel , when extending it sets down as soon as it starts to move.
The frame welds all look good , the rollers are worn some , but not terrible.
Any help would be appreciated.

[BLE373]

Our Alumascape TT had the same slide movement. Seems normal alignment motion in order to form seal when slide retracts and seats in trailer body.
The black marks most likely indicate guide material rubbing off. Not sure whether you have rollers or strips.