I have two Virtual Gravitys drilled differently. Had a 300 with both. I cleaned them, but did not soak them, rejuvinate them or anything like that. Then it seemed as if they died. I put them up for a couple of months and recently took them back out. Then now read the lane and hit as hard as they did new. I think sitting in the house for several months allowed the old to evaporate. So I would recommend doing one of the deep cleaning methods and then bringing the surface back to where you had it when you were having success with the ball.
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Nicanor (Ten On The Deck)