Apart from what normandy described i have seen this on a lot of reach trucks.....mainy after a lift ram seal change..if the rams are not bled properly u get a bouncing effect..also settings in the controller [parameters ]letting to much oil by pass solenoid valves ,,,,especially with full load ,,it would help to no what brand ;;

If the chains are scoring the Cylinder rods there are 2 probable causes,

1 the chains are not evenly tensioned allowing one to be slack and rubbing against the cylinder rod when traveling.

2 the operators are lowering the forks too soon while retracting from a pallet, binding on the pallet and allowing the chains to go slack. This will inevitably allow the chains to come into contact with the Cylinder rods, with the results you suggest.

I am sure there are many variations of this theme but the net cause will probably be loose lift chains

if you cant fix it with like a 400 grit or its deeply scored youll need to replace the rod or have it re-chromed