Stannah stairlift lubrication?

My mum has a Stannah model 300 straight stairlift. It is working fine and she has had no trouble except a small spring under the seat sometimes breaks and this I replace with any suitable spring I can find. Stannah have a minimum charge that makes this spring about £20 to buy so I improvise ok. Now to the main point. Should I be putting a smear of grease or a drop of oil anywhere?