This oscilloscope is being sold in an AS-IS / FOR PARTS condition since it is not fully functional.
Channel A tests GOOD with AC and DC sources.
Channel B has a damaged VOLTS / DIV knob. The knob must be adjusted (ie: jiggled / push-pulled) until the internal contacts are properly aligned, but once steady, it did test GOOD with AC and DC sources. This unit may have suffered a drop that damaged the knobs.
Tektronix 2235 100 MHz A/B Oscilloscope *AS-IS* Damaged B Knob