Search is your friends. The regulators are cable operated and prone to stretching. YouTube has some videos. Our forum host has a great DIY section on their website. Here is the link to the window section;
https://www.pelicanparts.com/techarticles/Boxster_Tech/77-BODY-Window_Regulator/77-BODY-Window_Regulator.htm
There is a temp bike cable adjuster fix (I tried it) that is not worth the time IMO. I tried the URO regulators. They failed in less than a year. I finally bought and installed the OEM regulators. Medium DIY project that requires some fiddling adjustments to get perfect, but doable.
There are a bunch of micro switches that come into play also. Any of which can cause function issues.