These projections are fairly easy to see if the cover rotates easily as you can look in the slots and see when the projections comes into view.  If the cover is very stiff you may have to get a pair of pliers that you can open, put each nose of the pliers into a slot and use it as a "key" to rotate the mama anti-clockwise - however this way it is difficult to watch for the projections to come into view.  In this case you either have to rotate it a little bit and remove the pliers and have a look - or gently pull one arm away from the body and look inside the doll to see where the projection is - this can help in lining it up.

Once the projections are lined up with the slots you can withdraw the mama.  Sometimes the mama is very tight and you have to gently lever the mama cover out by putting a small screwdriver about half way down into one of the slots and levering outwards GENTLY - you may have to repeat this in the other slot.  Before you do this the projections MUST be accurately lined up with the slots - or you will break something.

Once you have the cover out, the old mama may be wedged in the cover - all you can do is to hold the cover with one hand, the mama with the other and twist and pull.  Sometimes it will come out in one piece - other times (as shown below) it will leave the mama top wedged in the cover. You have to pull on the little peg to remove it. The pin is only held by a nail - if it pulls away then you must use a small screwdriver inserted ONLY in the holes of the top of the old mama (NOT the mama cover) to lever it out - don't worry if you break the old mama top.

Then you just put the mama cover and mama back into the doll with the "20 T" mark at about 11 o'clock so the cover projections fit into the slots and turn it clockwise until it stops - the "20 T" should end up at the top.

Small Mama Covers

With the smaller hard plastic dolls that have mama covers, these are often too small to fit a standard mama in even with ALL of the mama lip removed.  In this case, all you can do is to painstakingly remove material from inside the mama cover edge (the surface into which the mama fits).  A rotary drill with a metal toothed abrasive wheel is best.  You have to be careful not to take off so much material that you break through the surface, however the cover sides will have to be ground down fairly thin in order to fit the mama.  When you finally manage to push the mama into the cover you may find one or 2 problems.

Firstly you cannot get the mama cover back into the doll because it's sides have expanded somewhat when you pushed the mama in.  In this case you will need to take a sharp craft knife and shave off some of the lower lip in the mama hole in the doll until you can get the mama in.

Secondly you may find that because you've been unable to push the mama all the way into its cover it then jams up against the two pins that sometimes protrude towards the mama hole from the back of the dolls tummy and this stops the mama and cover seating properly in the hole.  If that happens you have to shave down some material from the top of these pins - the easiest (and less stressful for the doll) is to melt them down with a hot soldering iron (if you have one) inserted through the mama hole.