We have a Armstrong Ultra Sx80 furnace, model GUJ050D10-3A, with a HeatCraft Control Board, cat number 70k98 (40403001).

Everything fires up fine… thermostat, inducer motor/fan starts, then ignitor, gas, and the burners light, etc.
After the burners are lit for 30 seconds, the blower starts to turn on and then there are several rapid electronic clicking sounds from the control board, like maybe a switch or relay cycling on/off. Normally, I hear one click for the time relay to start the blower.
In this case, the blower never really stays on and eventually, the gas shuts off and the whole sequence starts over.
Sometimes, the blower stays on for a minute or two, then the relay/switch clicks rapidly and you can hear the blower start to cycle on/off.

If I let the furnace attempt to fire up repeatedly, the clicking sound then begins to occur when the inducer fan kicks on and then the firing sequence never begins, as I would expect. But mostly, it gets through the fire sequence and then the blower nevers fully comes on.

Could one of more time delay relays on the control board be faulty?
When wiggling some of the wires to the control board, the switching sound occurs rapidly as the blower attempts to turn. I checked the voltage from the 24V transformer to the control board and its putting out ~28V, seems to be OK.
I removed all the wiring spade connectors to the board and checked them for damage/corrosion, they appear fine. Re-attached the wires and it ran fine for a day, then this started again.

It would appear to be a faulty control board?
I either want to replace it myself or at least have this knowledge when a tech shows up.

Can someone help?

Thanks in advance. Jason