I have looked after four printing companies for some 15 years ,two have recently gone bust . I never had a contract as such although I did all their electrical work. Maintenance was basically lighting. The one would phone once a month with high bay lamps and office fluoro tubes to replace. Also breakdowns on folders/ stitchers/guillotines etc but not presses, specialists only.
Suggest you take a look round , identify the maintenance areas , if its just offices then lighting is the main thing, make a deal to call once per month and to replace dead tubes,say, usually other things crop up . Good if they agree to you calling on a regular basis , they come to rely on you , I've done all sorts for them, fixed notice boards etc.