I just got a new 26" mtb in Dec and already it's giving me trouble.. My two big issues are my stripped cassette, and my front tire doesn't hold air. The cassette seems to be an easy fix, but my tire is baffling me. I have already replaced the tube, i checked the inside and outside of my tire for any sharp objects, and the spokes from my rim are not pinching. Has anyone else had this tire issue?

Thanks