I don't like hammering t-nuts, too risky if you miss with your hammer swing. Also is easy to get them installed crooked, if you don't tap them in evenly.
I pull mine in. I use a special tool a friend of mine made for me, will try to grab some photos to share later. But, the 'old' way I did mine is inexpensive and easy!
A good piece of hardwood, fairly large size, padded with something so it doesn't marr up the playfield surface
Drill a hole through the hardwood for a fastener with the same thread pitch as the t-nut, use a healthy size washer under the head of the fastener to spread the load across the playfield, so it won't marr up or dig in, and pull it in.
