Intermittent operation or sudden unexplained impairment of the functioning of any item of hardware should be investigated immediately by a person familiar with the product, and repairs effected before user safety or product function is jeopardised.

Replacement of faulty or damaged parts should be carried out by an experienced person using the correct parts.

Where an item is still covered by the warranty given by the fabricator or installer of the product requests for remedial work under such guarantees must, in the first instance, be referred to that person or company.