I have had the dubious fortune of working on several of these. They are not bad saws. I DO NOT like the throttle cable setup, as it makes a gross bend right where it comes out of the case. The choke linkages are very often sloppy. I have had to remove the choke shaft and shorten the detent spring on the choke assy in order to get them functioning properly. They made those in different sizes up to 55cc, so the 4600 is pretty sturdy in the engine dept. Even though it is a clamshell engine, it has a bolt-down cylinder like the pro saws. This style of clamshell is especially nice to work on if you need new crank bearings since you can take it apart without special tools. The (plastic) chain oiler is adjustable and I have never seen one that didn't work. If you have not changed the oil line and impulse line, they're due. Sadly you'll have to remove the engine to get the impulse changed. The good thing is that the engine hold down bolts are seperate from the ones that hold it together, so you can remove the engine intact to change the line.
If you cannot find a case locally, drop me a PM. I think there is one or two of those at the local equipment salvage yard.