Hey Ted, and welcome to this fine forum !
When you say you manually closed the blower circuit, I assume you jumped the two purple wires together that go to the #1 snap disc and got the blower to turn on ? If so, then you should verify that the female electrical spade connections on the wires are making good contact with the male connectors on the snap disc. Sometimes it just takes gently squeezing the female spade connectors a bit with a needle nose pliers to make a better connection with the snap disc. Or as one poster recently found, the connection from the wire to the spade connector had deteriorated, which was an easy fix to crimp a new female spade connector onto the wire.
You're sure you bought the correct snap disc replacement with the correct temp parameters? I've also heard of a few cheap Chinese-made Quad snap disc knock-offs that were bad 'out of the box'. You can test the snap disc by gently heating it up with a candle to confirm that it "snaps", indicating the circuit has closed and that the disc is working as it should. Here's a how-to video that describes and shows this.
You're sure your stove is getting up to the temp needed to close the #1 snap disc circuit ? Your flame is brisk, yellow to white in color, with the correct fuel feed set rate? Your exhaust plenum and venting are clear of fly ash? If your stoves exhaust pathway is ash obstructed, or your door seals are bad, or the fire pot holes are clogged up you won't get optimum airflow through the fire pot, thus the stove may not be getting up to the operating temps it needs to kick the convection blower on.
Finally, are you burning decent pellets ? I mistakenly bought horrible quality "dirt in a bag" pellets my first year of pellet stove ownership, and the convection blower fan was off more than it was on that winter due to the poor heat output of the pellets. All just stuff to check before you throw stove parts at a problem that more often than not - about 75% of the time it is reported - ends up being an ash obstruction or a pellet quality issue that is causing the problem.
Check that stuff, and report back OK ?
Regards, DK