Before you try to replace the stripped gears in the convertible top transmissions, be sure to read the 101 projects writeup on the Pelican site. There are some preliminary markings you need to make before you take it apart. Otherwise it's pretty straight forward.
Bentley isn't expensive either.
https://www.amazon.com/Porsche-Boxster-Service-Manual-1997-2004/dp/083761645X/ref=pd_cp_263_1/147-4132863-2908364?_encoding=UTF8&pd_rd_i=083761645X&pd_rd_r=e1e0a053-09a7-4895-ba61-1b1e3a2a8de1&pd_rd_w=R5bGY&pd_rd_wg=zwwix&pf_rd_p=0e5324e1-c848-4872-bbd5-5be6baedf80e&pf_rd_r=C3KTDSNF0Z09MXSZSSJY&psc=1&refRID=C3KTDSNF0Z09MXSZSSJY
I'd get both. Don't bother with Haynes or Clymer they are both unsatisfactory.