Hi Chris,
In the parts list at the end of the manual, "EMT" and "EMC" are the acronyms that Tektronix uses to refer to electrolytic capacitors. On the 1S1, these are the power supply filter caps and there is also a small electrolytic on a switch as well. PTM is the acronym they use to refer to "paper or plastic, tubular, molded" capacitors. These are the bright yellow axial capacitors in the 1S1. Electrolytic capacitors definitely go bad over time, but whether "PTM" capacitors go bad over time probably depends on whether they are actually paper capacitors. The ones in the 1S1 probably aren't paper, but thought I should replace them anyway just to be on the safe side.
