My drive side pedals feels gritty or chunky and does not spin freely like the other one. How do I tell if the pedal is serviceable, and even then would it be worth servicing an inexpensive pedal? The bike is a Marin Muirwoods 29er so the bike was only $650 SRP to start with. The pedals are BMX-style flat pedals with metal platform. The only marking I see is what looks like VP, but I do not see any similar pedal VP's website.