If you have an older Balzers Pfeiffer Duo 1.5 mechanical pump that needs to be rebuilt and want to do it yourself, here is a link to a detailed procedure:

http://www.rtftechnologies.org/general/pfeiffer-duo15a.html

For parts or rebuilding of Pfeiffer Duo 1.5 mechanical and turbo pumps, here are some companies that we have used with success:

http://www.pchemlabs.com/services.asp

https://www.ajvs.com/new/product_info.php?products_id=12557&category_id=0