What is the version of the following sentence with correct punctuation?

Winter is the best time to have the mower maintained professionally oil change air filter and spark plug replacement but also sharpening of blades are then often offered more cheaply by lawn mower dealers or specialist companies
Winter is the best time to have the mower maintained professionally: oil change, air filter and spark plug replacement but also sharpening of blades are then often offered more cheaply by lawn mower dealers or specialist companies.