Cust complained about no heat.

Arrived at residence and immediately found bad spiral type HSI that was cracked-replaced with Sil-Nitride type.

Also suspected old W/R 50E/47-070 Ignition control-replaced with universal control.

Cleaned & checked burners, flame sensor(flame sense reading @ 3.8 uA).

Once furnace put back together furnace starts up right away. I noticed that the fan/limit was causing the ignition process to short cycle. Checked air filter-replaced. Checked fan settings-changed blower speed for heat from med to low speed. Observed furnace operation for half-hour to 45 min. Fan/limit no loger cycling and furnace operation seemed stable.

Followed up with customer about 3 hours later. Customer complained that she had to reset furnace at service switch because the furnace wasn't running. Furnace comes right on after reset-which tells me that the ignition control was into "lockout".

What am I missing?