Hi Erling, Welcome.....I have been restoring gas pumps for over twenty five years. In that time I have done a whole lot of visibles. These are very big and heavy, but also rather easy to restore since they had very few moving parts. In my opinion, all you need is a camera to photograph the complete, unrestored unit. As you remove parts, document each process with more pictures. Once you have all the parts removed and labeled....you can start the restoration. When all parts are ready...ie. paint, plating etc.....simply start with your last picture and re-assemble using the photos in reverse order. Nothing to fear and you'll be please that you did it yourself. Regards, Paul www.severngaspumps.com
I have one thing to add. When you remove the small parts and label them (like Paul mentioned), put them in Ziploc bags, label them with a marker and number them (just start at 1 and go up). Then when you put it back together it is easier to find the parts you need, just go through the bags in reverse order (along with the pics and documentation that Paul mentioned).
This applies more to an electric pump, since visibles don't have as many small parts, but it may help you keeping some things in order.