Many decades ago, I was constantly expriencing tearout on my plywood cross cuts on my Powermatic Table saw. Then an old cabinet maker who had several fingers missing, thus proving (in the 70’s era) he was certainly an experienced cabinet man, taught me this
If you use a table saw much, you will soon wear out the Throat. This is the part that you remove to change blades. The Throat is worn out when the kerf in it is not exactly the same width as the teeth on the blade. If you do different width dados on the saw, you need a throat for each size. If the Kerf in the throat is much wider than the teeth on the blade(s), you will experience tear-out.
Now, it does not seem as bad as it did in the old days, with 1/8” to 3/16” wide carbine teeth on really heavy blades, but the problem will still exist if the kerf in throat gets too wide.
A new throat can easily be made by using the old throad as a guide to cut a new one from a 3/8” thick plywood scrap.
After you band saw, or in some way cut the outside perimeter, you now place it in the saw with the blade totally retracted.
If the new throat sits too low, and it should, locate the 4 small feet that it is sitting on. Mark their location and place a small flat head screw on the bottom of the throat where it thouches these little feet.
Place the new throat on the saw and adjust each screw until it is exactly flush with the table. If anything, place it 1/64” above the surface of the table and sand down the front edge so that the panel will slide over it and not bump into it.
Now place the fence over the new throat making sure it will not me hit by the blade and slowly raise the blade while you hold the other long edge of the throat down with a piece of scrap wood.
I would suggest that you cut severa throats at one time and keep them aroung when you need a new one or change from one dado blade to a smaller one.
Hope all this is clear, and look forward to your comments.