Brass sleeves were commonly used on EMs. They seldom ever wear and the theory is you can put them in a tumbler and they will work for many more years to come ! I prefer plastic sleeves.

All the EOS switches can be found at rttb.com.au

http://www.rtbb.com.au/catalog/index.php?cPath=44_158&osCsid=e9dac1bf8fbd1b4baa07864e15377ea8

There are two different styles, depending on if you have installed a full flipper kit. This is the more common one to ADD to a flipper kit standard EOS

http://www.rtbb.com.au/catalog/product_info.php?cPath=44_158&products_id=2911