The regulator when correctly set-up will almost roll down just from vibration. The mechanism is not very complicated. The regulator assembly has to be removed to do any maintenance on it. Are you getting any interference from the window channels, wipers, etc? If no you need to pull the window regulator out and probably buy a rebuild kit for the geared shaft that attaches to the handle. This assembly is riveted in place so buy a rebuild kit before you tear into it. When you reassemble, lube it with a high quality grease. I rebuilt both of mine and they have been trouble free ever since. In fact going over bumps they roll down a little bit. I will also share with you that any aftermarket regulator will strip out and fail very quickly, when I sold parts original assemblies were a big seller for this reason, the originals are very high quality, most are still working some 60+ years later.
