Having had the same table design as you I can understand what you are talking about. There is no easy fix. I would recommend you add a X axis slave motor and another piece of gear rack to match the master side. This would require very little work to add the rack.
The gears and rack on your table do not have precision tolerences. This causes one side of the gantry to travel a difference distance than the other. In addition the gears are very noisy and rough as they travel along the racks.
That said I did get alot of use from mine before I upgraded to dual motor X axis. With some fine tuning I got it to work pretty well. The 2 things that helped most were;
1. Park the gantry in the middle of the table and adjust the cross shaft alignment so there is no wind up or (ratcheting). This will minimize the ratcheting effect when going from end to end of table travel.
2. The cross shaft pinion preload is critical. Put just enough spring load on the pinion so it seats in the gear rack. This will require VERY light pressure.
Keep the rack well lubed with a dry silicone type lubricant so it does'nt attract dirt.