There wasn't much hi-tech about the old Concord air carts. Here's a couple shots of how I check for blockages.

Notice the nice uniform splotches of seed and fertilizer, slightly ahead and below the shovels. You need to turn off the fan and de-pressurize the tanks before you fill. When done filling and you have the lids sealed, just turn on the fan, walk back and give the feed roller crank a turn or maybe a turn and a half. Walk behind the seeding tool and check that there is a splotch for every shank. They will also be extremely uniform in size when all is working. If one is a bit smaller, it's time to investigate as there may be a small obstruction. I have noticed that the seed runs have a tendency to wear out obstructions quickly and are to a large measure, self-cleaning. Drove my seed truck through a small thicket of trees once and didn't have the tarp rolled out. When I started filling, I noticed a bunch of twigs in the filter baskets. They caught the lion's share but I could see that some made it into the cart. While seeding that load, I would stop every mile and check for blocks. Never found a one and never found any of the twigs either. Not wanting to push my luck, I now make it a point to roll the tarp before driving through thickets.