Its very difficult, if not impossible to buy mirrors for these smaller telescopes, and even tougher to fit them! Your best bet would be to take it back to the shop you purchased it from, and if its under warranty, make a warranty claim. If no longer under warranty you may just have to purchase a new one. You could try a specialist optics (telescope or camera) store and they may be able to replace, but it would likely cost you as much for the repair as a new one.
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Its very difficult, if not impossible to buy mirrors for these smaller telescopes, and even tougher to fit them! Your best bet would be to take it back to the shop you purchased it from, and if its under warranty, make a warranty claim. If no longer under warranty you may just have to purchase a new one. You could try a specialist optics (telescope or camera) store and they may be able to replace, but it would likely cost you as much for the repair as a new one.