On your first typewriter, there is a small gear right beside the escapement wheel that engages whenever you press the tabulator.  This is the tab brake.  On one side of it (I believe the right hand side if the keyboard is in front of you--which it should be because you will need to take the roller off.  This is done by pulling a lever on the bottom right side of the carriage and just lifting out the platen.  The left knob will stay in place.  Now, two bolts hold on the plate behind it.  Remove these, the plate and the big back roller and you should clearly see the tab brake.  Now for the spring.  The rack the spring latches onto goes further out as it gets to its bottom.  Move the spring about one or two notches higher, and test the tab.  You don't want it to move too freely because the carriage will move too fast and the tab stop will be hit with too much force.  It may take several tries, but you can get the adjustment you'll need eventually.

Now for the KMG:  Take off the right-hand top rear plate, and you'll see a rod with two bolts in the middle.  Unscrew these and pull in the rod just a little bit, and try the tabulator.  You don't want to adjust it in too far because the tabulator finger will scrape across all the stops, perhaps even stop at all of them as though they were all set.  Again, you'll need to play with this adjustment a little bit until you get it to where the tab finger will stop the carriage only on the set tab stop or tab stops.  --I'm going over some old posts, so this was designed not only to help this particular individual, but anyone else who is encountering a similar problem.

It always feels good when you can conquer a new task or repair.  I know it well.