Both these parts in combination with a linear rail and pulleys will improve the x-axis of the atomstack if yours is engraving a "wonky" straight line.

Need one LinRailCarriage print and 2xLinRailEnd prints.

Linear rail used;
Twotrees MGN12H 500mm Linear Sliding Guideway with 1pcs Linear Bearing Sliding Block for 3D Printer and CNC Machine(H-Type,Black)

2020 V-Slot Aluminium Profile (this is only needed if profile has slots top and bottom. Older atomstack should be ok with slots on each face) - Cut to Size mine was 525mm

Pulleys GT2 Idler Pulley Timing Belt Pulley 20 teeth 5mm Bore For 3D Printer CNC 6mm Width Belt

2xM5 @ 50mm, 2x10mm, 6x 7/8mm 4xM3 @ 6/7mm, 10xM3/M4 @6/8mm for rail. T-nuts nylon nuts star washers