I'm not 70 yet, but I have been bleeding brakes pretty much the same way you have for 40 years or so. It still works on my 91_240.

I do put a clear plastic tube on the bleeder and drop it in a jar with a little brake fluid in it. That way I can see the fluid come out and bubbles (if any) and if I'm not quick enough on the wrench to close the bleed screw I only get fluid back up the tube, not air.

I have the pedal pusher person push (say that fast four times) slowly and open the bleed screw while they are pushing to see fluid come out of the bleed screw through the tube and into the jar. I then close the bleed screw before the pedal pusher person lets up on the pedal, also slowly. This cycle should pump fluid from the master cylinder to the open bleed screw with no air getting in the system unless the master cylinder reservior runs dry.

Four times is generally enough unless you are trying to flush the system and replace the fluid, then it is just repeat the cycle until the fluid comes out clean.

Have fun, and let the grandson get dirty too. He needs to know how to do this too.

91_240