Ashton Humphrey answers: "they were not very good and most are way past their life expectancy. On the plus side they are easy to replace. Basically plug and play. New laser assemblies are easily sourced for under $15. If you get one of the cheaper ones before you go installing line up the ribbon cable with your existing one on the laser assembly . Some of the china clones will have the tab just slightly wider than the original which can offset the alignment. Most I've come across this was not an issue but over the past few years I have come across a couple that needed a slight trimming."Retrostuff adds:" Don't forget, these are almost 30 years old. Dirty disc message can also be caused by dried grease on the toothed rod. Clean that up and apply new grease. Then, move it back and forth (e.g. with the Service Shell or by playing an audio cd in shuffle mode). If you need a new pickup assembly, VAM1201 and 1202 are substitute parts. Depending on the source and quality, the end of the ribbon cable might not fit, like Ashton Humphrey said. I've found that they are not only wider but sometimes also thicker than the original and need to be filed down."
[Thanks, Dale Powell]