Good coverage in the 1969 Chassis Service Manual starting in section 12-35 for the procedures if you want to tackle this yourself. I would not recommend disassembly of the gearcase unless you want to bolt it back together - the factory procedure is to drill out the staking tabs and bolt it back together using "screws, nuts and washers.....contained in a service repair package". If the gears are O.K., I recommend replacing the brushes, cleaning the armature, outer cases, replacing the mount cushions: paint and detail and you should have a pretty good looking and functional part. I have only seen one business advertised in Hemmings in a good while for restoring electrical wiper motors - might be more options on the net, but I have no reference for you. Parts might be tough - if you have a friendly dealership, if they don't list them as current have them look them up on the locator - you might get lucky. You can also try a local AC/Delco service parts company if there are any left around - I haven't had the occasion to buy from one in a couple of years.
Please see the following - these are the only details I have ever seen different between the original part # 5045605 RS wiper motors assemblies, and replacement motors like the # 4918442. The end frame (rear bearing support) cover is stamped with the part number, there usually is a sliver tag with part number and date code as you see in the pic (now available as a repop, correct), and the 2 drilled holes for the directional valve (solenoid coil operated) mounted directly on top of the motor housing, as you know. The valve and valve parts are produced by Impala Bob's that I have seen - he apparently is the primary supplier to a lot of the catalog houses, but will sell components if you can make repairs to your original. The valves are pretty fragile, and break easily when old.I can supply you with part numbers if you don't have access to a GM parts manual - tell me what you need.