Have found the best door operator information on this forum. This Genie SP99 is at least 30 years old, installed in unattached garage which is used as workshop and unfinished inside. The Genie is operated about once a month and shows no signs of wear. The remotes died long ago and are long ago-discarded. Do not really need the remotes anyway. Recently the door twice has opened without explanation. So now I unplug it except at time of use, quite inconvenient. I might rewire the overhead receptacle with a wall switch control for convenience.