By the look of it, Unilab make bench-top power supplies, so we're probably talking about something a bit more complicated than a wallwart.
Do these PSUs carry the Class II construction mark (square-in-a-square)?
If not, then they are Class I, and should have an earth connection, so you'd be wise to reattach the earth as Alan suggests. Is it obvious where the earth was snipped off from?
If it is the case that these appliances are Class I, you should report the previous tester to your school authorities. In fact, this issue should be reported as a 'near miss' on your accident/incident reporting system.
The previous tester doesn't appear to be competent to carry out in-service I&T, and has placed the users of this equipment in substantial danger.
C&G 2377 -01 & -02