Use the Lend Engine to remind you when regular servicing is due, delegate to engineers or volunteers, and create an audit trail of maintenance.
If your items need regular servicing (perhaps an annual electrical test), then it's easy to schedule a repeating service. When the next service is due, you (or your service provider) will get a reminder that work needs doing. If it's the kind of work that prevents someone borrowing an item - perhaps insurane prevents you lending your items where electrical test has expired - then that's easy to manage as well.
Perhaps an item is found which needs repairing or cleaning. Simply move it to a 'repair' location and assign ad-hoc maintenance. While it's in the repair location, users can't borrow it.
Some items need washing, servicing or cleaning after every loan. Lend Engine can be set up to schedule a maintenance activity after each check-in. Simple.
If you need to store service reports, or any other document, just attach it to the maintenance activity.