Bill Cullen ( I can’t find anything specific on why he left - it wasn’t the game show rigging as that didn’t impact PIR; he continued to host a bunch of other big game shows)
Don Pardo (dropped when show moved networks)
John Gilbert (show ended - revivived in 1972)
Then Barker (Cullen was considered but I think the schedule or his health was an issue)
one of the few shows to air on all 3 major broadcast networks at some time in it’s history.
The revival of TPIR in 1972 was deemed to strenuous for Cullen to host. Cullen was stricken with polio in his youth and that had some lingering effects.
I would venture a guess here and say that it wasn’t just because the show was “stenuous”. If I remember correctly, Cullen was always behind something be it a podium, desk or some stage prop. I think he was mostly seated, too. Probably the new 1972 TPIR format required the host to be “out in front”, a la Barker and Carey. Having to do this would reveal that Cullen had physical afflictions.
Cullen was just on everything. Seemed like he was darn near part of the family.
#Black&WhitePhilco
I am fully confuzzled, now. I clearly recall Trebeck hosting a game show where a new Monte Carlo was awarded to a very good looking woman.
He was replaced quickly.