Green’s Dictionary of Slang

fritz n.2

In phrases

on the fritz (adj.) [? German proper name Fritz and thus propagandist dislike of all things German, or fritz as onomat. for the sparking of a faulty wire or connection] [20C+]

1. of a person, unhealthy, out of sorts.

2. (also away to the fritz) of an object, not functioning properly; thus antonym off the fritz, working.

3. (also fritzer) of a situation, position, job, in jeopardy.

4. (also on the fritter) of machinery, broken down, not working.

5. impoverished.

put on the fritz (v.) (also put on the fritzerine, put the fritz to)

[20C+] to spoil, to render out of order, to put a stop to.