Priport D3440 Part of image missing

[westpest]

Have DX3440 that has 50mm of image missing from LH side of page as read, straight line . Have tried the following;
Thermal Head
MPU Board
Lamp
Lamp Stabilizer
PSU
Drum
OP Panel
Manual says that masters are cut full size every time ,so I am at a loss. Have tried with A5/A3 original no change.Have tried opening guides on paper tray in case there is a sensor that is detecting paper size and cutting master accordingly no change.....
Any advice appreciated

DanF