Positive welding problem

[gijs.wh]

Recently, my spot welder started giving issues
it's a CNC-controlled spot welder with 2 pneumatic cylinders to press down the electrodes. in combination with kweld and kcap (also tried quite a few other welders and power sources)
it used to work perfectly but recently, the left side (positive electrode) stopped welding, while the right side of the weld is excellent. on the left side, the nickel doesn't even stick. kinda lost here I have already tried different power sources and welders
any clues on what this could be

 

[jetpackjbd]

I’m assuming you’ve checked, do you just need a new electrode? I’m not experienced with welding but I’d assume if one side is more warn down than it’ll perform worse than the other.