Grumpy, thanks for the advice and the clarification. Indeed, the first time I tried to start the engine, the pull cord retracted violently.
I have since discovered that the PTO does need some weight on it. This is to provide the needed momentum to carry the piston past TDC. Also, the pull-start mechanism on this Briggs is not very smooth or robust and it hasn't held up very well with age. This surely doesn't help.
