[Beav]

Bad u-joints will make a vibration under acceleration, not decel - if they do it wopuld be the first time I've heard of it thirty-four years.

Axial play (up and down across the yoke) isn't good, it would cause a vibration, accel or decel. Think of it as two off-center shafts, spinning together.

Radial play (where the cross of the joint slops around sideways in the cups) will cause the accel vibration.

Of course the driveline shop would say staked-in joints can't be repaired, they make more money building a rebuildable shaft...

Be certain when bleeding 'uphill' that the cylinders aren't tipped in such a manner that air may be trapped at the far end from the line at the slave or the end next to the line at the master. Think about it, you'll see what I mean. However, since it worked for you the first time, you should have equal success this time.