I've restored a few Galaxy machines and parts are available from Pinball Resource, or our parts site
www.rtbb.com.auDrop Targets, pop bumper caps are mainly available from PBR - and we (RTBB) order from them often. If you have a shortlist of what you can't find locally, we would be happy to help out.
Rubbers, posts, coils etc - we have most on the site to start you off.