The 71-year-old rocker believes he has around 2,000 cassette tapes with recordings from his legendary band, which he'd love to listen to again, but he doesn't have a tape player to play them on.
Jeff is quoted by the Daily Star newspaper's Wired column as saying: "I must have about 2,000 cassettes that I still haven't listened to for about 20 years.
"I haven't got a cassette player for a start!
"I would love to check some of those really old ones out because there might be something I really love there now."
Last month, the 'Every Little Thing' singer released his 14th studio album with ELO, 'From Out of Nowhere'.
The record is about holding onto "hope" in dark times.
He said: "'From Out of Nowhere'" - that's exactly where it came from.
"That's the first one I wrote for this album and it's kind of like that."
In 2014, Jeff took up some production duties on Take That's seventh studio album 'III', but he ruled out a collaboration on 'From Out of Nowhere'.
When asked about the possibility, he said: "No it's just been me doing it. I haven't really got any plans to work with anybody really - just by myself, doing it, making the album."
Considering his previous production services there was speculation of a partnership with Gary Barlow, but Jeff was adamant about flying solo.
He said: "I like Gary very much - although I haven't seen him for a while."
Jeff has seen a renaissance in recent years with a new generation embracing the legendary rockers off the back of a successful tour and record.
ELO played a triumphant set at Glastonbury Festival in 2016.
He said of the performance: "It was just a great end to an amazing tour. We did 19 shows and sold them all out in big arenas, so I can't complain about anything right now."