The retaining bolt may be too tight. When you change the oil check the condition of the canister top o ring (or if it even has one). Also make sure there is a washer between the bold head and the top of the canister. When you change the oil make sure to cover the new o ring in fresh oil and use a new washer for the canister top and bolt, both will be supplied with the filter cartridge kit. Is the oil pressure good?