i'm sorta new to the hobby about 4mos andI have recently purchased a savage xl. was a previouse savage 25 owner.

My issue I am having is that when I hit the throttle front wheels will spin but back wheels don't move. But if i spin wheels by hand all the wheels will move as normal. I have takin the transmission apart but didn't find any flaws no shredded gears everything seems to work as it should please help...