Once you have your antique slot machine mechanism disassembled, it is absolutely mandatory to remove all of the old dirt, grease and oil from the various parts. In many cases you can restore life to a dead machine by simply disassembling it, cleaning/degreasing the parts and then reassembling it with fresh lubrication. This won’t always work, particularly if there is rust on your mechanism, but it’s an important step in any restoration.
The subject of degreasing vintage slot machine parts is not a complicated topic. There are several ways to go about it depending upon the equipment at your disposal, but essentially the basic process is the same. You need some sort of solvent, a way to immerse the individual parts, a couple of hand-held wire brushes and some good, old fashioned elbow grease.
There are a ton of commercial degreasing products that you can find at your local hardware or auto parts store, and they all generally work pretty well. In a pinch you can use spray-on oven cleaner or even dishwashing detergent, but typically the commercial products will be both cheaper and more effective. You can often buy the degreaser in a concentrated form and mix it with water to the strength needed for your particular job. Many modern degreasers are also biodegradable, making them easy to dispose of once the job is done.
For small parts, carburetor cleaner is an ideal solvent for removing old grease, and you can get it in a paint can with a built-in parts basket. Carburetor cleaner is pretty toxic stuff, however, and you may end up with a disposal problem once it is loaded up with grease. Generally you cannot pour it down the drain safely.
If you have access to a parts washer, that’s most definitely the easiest way to go. The photo to the right is one of the basic models from Harbor Freight. Just a note about Harbor Freight: Many people dislike Harbor Freight because of their cheap, imported tools. Although I don’t shop for heavy-duty tools at Harbor Freight, they are a great source for inexpensive (read disposable) tools and miscellaneous supplies. If you have one of their showrooms near you, pay them a visit and check out their stock. They generally have at least one parts washer on display. With one of these washers, you can load up the basket with many slot machine parts, then use the built-in pump to recirculate the degreaser/solvent over the parts while you do something else. This is a very easy and effective way to go about degreasing, and the washers come in multiple sizes and prices with small models starting at less than $50.
If you don’t have a parts washer, though, you can still get the job done. Get a large plastic tub or bucket, drop in your parts and then cover them with degreaser. Let them soak, stir them around from time to time, and use a wire brush or a stiff plastic bristle brush to attack the grease. This may take a while, but it works just fine.
After you’ve gotten rid of the grease, it’s usually a good idea to rinse the parts thoroughly, and possibly even clean them with mineral spirits to get rid of any residue left from the degreaser depending on your next course of action. Generally you are going to follow up your degreasing processes with some sort of rust removal and rust protection, and you certainly don’t want any residue interfering with your rust prevention efforts.