Weekends can be real slow on here starting about noon on Friday especially this time of year.
I'm no expert when it comes to the hose connection.. My first thought- the hose pressure when connected is more direct to the tatle tail.. thus a good stream.. While the muffs only supply water to the water pump and sometimes don't do a very good job of that.
Are you sure there is a restriction ?? you say the pump (looks) ok ?? Also when you pulled the pump did you get that drive shaft seal on top of the housing adjusted correctly ??
Had one that I could not get a good stream with muffs -- was fine when submerged in water.
Any way good luck maybe someone will show up with more info..