If a casino no longer has a Strike Machine, you might be able to buy strike straight from the cashier's cage. Here’s a list from SilverStrikers.com on the casinos that you can buy obsolete strikes straight from the cage:

Circus Circus, Tropicana, MGM Grand, Hard Rock (Good Luck Here), Harrah's, Boulder Station, Palace Station, Riviera, Fremont, Slots A Fun, Plaza, Fiesta, Stratosphere, Excalibur, Mandalay Bay.

I hope that helps.