Dwayne,

I'm not familiar with this particular engine, but usual approaches may suggest something to you... The only MERCO I have is an old 1-plug, 2BB 61, which looks like it has a fine taper (small diameter change) and no keyway.

1) If it has a taper to the inside of the thrust washer, it may work if you disassemble the engine to where just the shaft and case are together. Rest the back of the case on a flat wooden block to prevent marring the backplate mating surface. Use another piece of wood, possibly a scrap of motor mount maple, resting on the end of the prop threads, and tap it lightly (at first) with a hammer. Keep the wooden pad at the end of the prop screw square to the shaft, and strike square, directly above the shaft. Do not hit it any harder than necessary!

2) Fine splined thrust washers are usually seen on 1/2A engines, like Cox. Same approach works.

3) If you can see a key in a slot in the front of the shaft, you might cause some galling with the above method, but it will usually work.

Gear pullers usually don't suit this; they mess up the thrust washer too easily, unless the "claw" ends have an unusual amount of 'surface' gripping the back side so as not to.

Time for someone experienced with this particular MERCO to comment...