Tektronix part number 260-0834-00 refers to a small DPDT switch. It is used in a variety of instruments. It is used both as a power switch and for switching signals. They may have been sourced from more than one switch maker. Some of them fail, which can be diagnosed by an improper feel when moving the switch. When this happens, it can be dangerous because in some cases the two poles can be bridged. For a power switch, this can be a short from mains hot to mains neutral. As of January 2019, replacements for this part are readily available, both new and NOS.
The C&K model 7201 is one of the switches that was marked as 260-0834-00.