PIP needs very little maintenance. The most important thing is to keep the battery charged up. You cannot over-charge PIP but the battery may be damaged by leaving PIP fully discharged for long periods.
Should your PIP become dirty it is quite all right to clean it with a damp cloth. We use spray furniture polish. Avoid getting polish on the wheels.
Keep PIP away from sand or water. It will not be accurate on a carpet and the fluff from the carpet may cause problems.
Keep Blu-Tack away from the drive belts!