I just did them up about that tight.
If you need to get the motor off the base you will need a puller to get the pulley off the crank. I have a 3 jaw here thats probably from supercheap, its small to medium sized, i got mine off with that easy peasy.
Pay attention to the tensioning instructions for the belt if the sticker is still on the back of the base.
Last thing you do is put the belt cover on underneath, damn bloody belt falling off.
If the belt is slipping heaps you are trying to cut the grass too short, or the ends of the blades are bent up from hitting a rock etc or a combo of both. The drag of the plate/dsic on the grass would be a fair bit i imagine.
And make sure you have a rubber cap on the spark plug lead. If you drag it backwards in long damp grass the spark will earth on the grass back to the frame and zap you through the bars. My grandfather thought it was amusing.
They are a good thing. Well ballanced and not much more work than a regular mower and will cut heaps more grass in the same time.
Keep your eye out for a mower with a side pull motor with the electronic ignition. One of those will fit on it. Even if you get the mower, get it running, rebuild it or whatever and just have it sitting there as a spare motor.
Cheers, Bob.