My group makes sure the company's analytical instruments are working well. Most of the work entails performing routine maintenance & repairs, and inventory management. Sometimes we design our own parts to replace obsolete or depleted items. So when we've done a good job, we get a bit of downtime.
The most difficult part of the job is meeting the desires of management and the analysts who operate the systems we service. Everyone wants us to make fast, high-quality, inexpensive repairs, but that's not always possible with our budgetary and supply-chain limitations.
All the service engineers in my group like to work with their hands and fix things, so the most enjoyable part of my job is the camaraderie I have with them.