I have a 3 year old Husquavarna lawn tractor with a 21 horsepower B&S 2 cylinder engine with 104 hours on it. It started to backfire and had little power on the right cylinder. Afer doing some looking I took off the valve adjustment cover and the top push rod barely moves so I am assuming a lobe wiped out on the camshaft. I am very good at working on cars but I never did a small engine. What does it take and how do I change the camshaft in this engine? Thank You.

Cam may not be problem, Binding or broke spring could limit travel.
Shop Manual best if considering Camshaft replacement.