Jeff B. brought to my attention that the purge-air flow in the combined volume of HAM4, HAM5 and HAM6 seems to be fluctuating in a periodic fashion -> I investigated and found that the low pressure output pressure regulator supplying purge air to the LVEA is stuck -> As such, the output pressure of the regulator (to the LVEA) is fluctuating between the nominal 1 psig and 1/2 psig as the input to the regulator fluctuates between the nominal band of 120 psig and 80 psig -> I'll order a part and get this fixed but in the meantime, in-chamber work can continue.