The first thing I would do is re check all of the racks / bars / pins etc.
Bad alignment is the normal culprit for travel resistance in a pulley system. If the exterior frame is level ( use a level or a laser to check) and all of the pulleys are aligned ( straight edge / device aligned- not sight aligned) then the next option would be a dry spray lubricant. There are many options out there. Teflon, Graphite, Synthetic, etc....
After that you just have to wait for the cables and pulleys to "seat" themselves over time. Once that happens they tend to travel a bit more freely.
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