WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
Building, troubleshooting and testing of these amplifiers should only be
performed by someone who is thoroughly familiar with
the safety precautions around high voltages.
Indeed he is. He did go thru a rough spot for a while (i think the numbers of us having similar experience are legion). The tube coolers can be had direct from Bill (he did mention a sale on cooler for the EL34 & the like on the JoeList) or from the new Parts Connexion. He has a number of other dealers, including one in England (i helped him pack up an order when i last stopped by to visit - a couple or 3 years ago now - and earned the coolers on my 5-buck amp).
For that dealer & others you would have to contact Bill.