I know that Steve at The Pinball Resourse sells the tees. Very nice and helpful guy. I decided to replace mine with some practice balls I got at Walmart for maybe $1.50 and not use the tees. Just drilled a hole in the bottom and put it over the lamp. To reinforce the hole I bought little plastic grommets from my local hardware store, maybe another buck, and inserted them into the hole which gave the ball a better base to rest on.

Before
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After
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