Most likely all of the metal pieces are still good and you just need to replace the rubber part. The pinch bolt should probably be left alone, pop the ball socket off of the top frame while the top is in the 'service position'.
If your top is making bad noises it may be a cracked gear in the transmission for the top. Here's a tech article about how to replace the gear:
https://www.pelicanparts.com/techarticles/Boxster_Tech/BODY_Convertible_Top_Gear_Replacement/BODY_Convertible_Top_Gear_Replacement.htm
For a PDF manual, there are eBay sellers that have it online/CD for about $5.
For most owner maintenance, the Bentley Manual
https://www.amazon.com/Porsche-Boxster-Service-Manual-1997-2004/dp/083761645X is as good as the PDF version of the service manual.