Fatal Error 401

This error is Error 401: “filter wheel error” “Filter wheel did not move to its photo interrupt in a reasonable time, or cannot find its photo interrupt.” __________________________________________________________________ It was discussed here: https://www.labwrench.com/thread/172848/fatal-error-401 __________________________________________________________________ I overcame it successfully on my spectramax 190 machine. __________________________________________________________________ I opened the instrument up and found that during startup, the filter wheel did not move at all. When I replaced the motor that moves the filter wheel with this stepper motor https://www.amazon.com/gp/product/B07PNV7RBW/ref=ppx_yo_dt_b_asin_title_o05_s00?ie=UTF8&psc=1 (with the shaft sawed off to shorten it to fit into the instrument) caused the motor to move again. The error persisted even though the motor moved again. Then I wiped the mirror and filter wheel with an alcohol pad. This fixed the error. __________________________________________________________________ In case that amazon link goes down, the motor is "Iverntech Nema 11 Stepper Motor 28mm Body 1.8 Stepper Angle 0.8A 2 Phase 4-Lead with 50CM Cable for 3D Printer, CNC Machine and Robotics" __________________________________________________________________ I fixed the problem, but because my instrument had damage to the dust filter, it sucked up dust and the problem reoccured after a week of use. Wiping down the mirror/wheel fixed it again, but I'm now trying to replace the dust filter. I need help figuring out what the black foam inside this instrument is because I think I need to remove some of it to get at the instrument: https://www.labwrench.com/thread/267116/black-foam-in-spectramax-190 __________________________________________________________________ Happy to share knowledge so we can work together to keep our dinosaur lab equipment alive