I just put twelve custom gobos into six of my units. The hard part is gritting the retaining spring out the first time. I used a small screw driver to get under it and get it out. We bent a small tab on the end to make it better next time. The clearance is very tight so do not bend tab to much. All in All it was not too hard but it could be easier for sure. Take off cover locate the gobo to replace a headlamp helps remove spring that retains the gobo take gobo out put new one in and replace spring and cover.