You've stumped me with that one, Junkman. I worked on a few antiques and usually could find parts, but I did run across a couple for which parts were no longer available. But I've never seen or heard of an IR904. Some of the other IR models have that Allen screw in the handle with about a 1" cylinder of some kind of felt or fiber material that you soak with oil and a sort of siphoning effect makes something of an automatic oiler of it. But the ones of those I've seen didn't have a screw in there. As for Marvel Mystery Oil, I know a lot of people who used it with no ill effects that I know of, but Marvel Air Tool Oil is what I used. Of course I got it by the quart which would probably be a lifetime supply for most folks. /forums/images/graemlins/laugh.gif Does that tool have another oil plug on the side? If so, that will be the one that is supposed to have motor oil in it. The ones that have the motor oil in them do not use grease. Or is there one of the little dimple/ball bearing grease fittings anywhere on it? </font><font color="blue" class="small">( the part that retains the socket is worn down to nothing )</font> Are you talking about a little metal split ring? If so, it's actually called the "socket retainer ring" and under it is a "socket retainer O-ring" (a rubber ring that may be round like most o-rings or may be flat like a tiny rubber band). Those two parts cost $.30 to $1.00 each unless they're on a Snap-On and then about $3. /forums/images/graemlins/laugh.gif And they're easy to change, but I learned that most mechanics don't know how. </font><font color="blue" class="small">( the sides of the 1/2" drive are rounded to some extent )</font> That's called the "anvil" and I sure replaced lots of them when they either got rounded or chipped. I don't know whether a new one would be available or not. It's my guess that it would not be worth the expense to fix, but you might contact an authorized Ingersoll-Rand service center and they could find out from Ingersoll-Rand whether parts are available and if so, get a copy of the parts list and exploded view. I think Ingersoll has those for everything they make. I sure would like to see some pictures of that tool.