Betamax VCRs provided three recording speeds: Beta I (fastest, smallest capacity), II, and III (slowest, most capacity). The Beta I recording speed was used with the earliest Betamax VCRs, but was dropped after Beta III was introduced in 1979. However, many consumer machines continued to support Beta I on playback only. The recording speed was usually selected manually, with a switch, while the playback speed was selected automatically on later models. The SLO-260 (1976) is one of the oldest Betamax VCRs and only supported the Beta I recording speed. Beta II or X-2, as it was first called, was not introduced until 1977. The SLO-260 cannot play back tapes recorded at the Beta II or III speeds. If you are using it to play back tapes made on newer Betamax VCRs (i.e., after 1979), this would likely be the source of your problems. If you are trying to play back tapes recorded at the Beta I recording speed, you likely have a problem with the speed control in the transport. The plastic gears in the transport can wear out, but worn gears produce visible and audible ‘wow’, not an increase in the tape speed. Footnote for those with similar problems with newer Betamax VCRs: Your machine may have a problem with the automatic playback speed detection or, if the playback speed is selected manually, a problem with the speed selector switch. You should open the case - with the unit unplugged - and give the machine a thorough cleaning. It is possible that a dirty sensor is causing the problem. Cleaning is a good idea with any VCR more than 10-years old, regardless. If the playback speed is selected manually, you should check the operation of the switch to ensure it is working properly and replace it if not. Failing either of these solutions, you may need to have the machine serviced.