Laser Engraver Forum

gday, my names FaydenOr, i am new to this and just got a chinese co2 laser cutter engraver 2nd hand. i think its ms1280d, i am setting it up and have leveled the table and started adjusting the beam. i got the tube to fire in the center of the first mirror and when the second mirror is close to the tube, it fires a small dot in the centre but when the second mirror(on the left of sliding arm) is far away from the tube, and the laser is shot, it makes a large burn dot, a lot bigger then the first. ? i have swabbed the mirrors clean but still the same. i am hesitant to swab the tube cause its expensive and i couldnt find anything telling me you could. i guess i am asking if anyone has had this problem before or know any possible soulutions/actions.
thanks for reading all.