Loud Audio Spikes/Pops During Playback/Digitising Cassettes - Sony TC-WE475

Hiya,

Just wondering if anyone could offer any advice on the issue I'm having. So about a year ago I decided to start digitising my old cassettes (old UK rave recordings and DJ mixes I did from the mid 90's through to the early 00's before I switched to Minidisc). So previous to this I'd been playing cassettes on a glorious old Technics RS-M10 deck. Sadly though, it has a habit of chewing up tapes and the playback speed was slightly slow. Not being familiar with any kind of servicing or maintenance work on vintage decks, I decided to buy the last produced Sony deck the TC-WE475. I'm not going to lie, I didn't do much research on the deck, just the fact it was the newest Sony deck I could get and that I found a serviced one (belt change and calibrated etc) on ebay for a decent enough price was enough for me to pull the trigger. All was fine for the first few months but slowly, I started to notice some loud audio spikes/pops in the recordings. At first I thought possibly it was just some of the tapes I was recording, most are 30 years old. Not the end of the world as it was only a few pops and I could zoom right in on the recording and lower the volume right down. They're only a millisecond or two, so not even noticeable on the recordings. The problem started to get worse and I noticed that the clicks/pops/spikes (whatever you want to call them) occur at pretty much equal spaces. It started off about 10-12 minutes apart but has now got to a point where they're only about 2:30-3 minutes apart. So. Much. Editing!

I run the decks output into the input of my audio interface. Originally it was a first gen Focusrite 2i4. Then I moved my music studio to a new room so got a Universal Audio Volt 476P). I hoped possibly the issue would disappear with the new interface, but sadly it didn't. I record in Audacity. My first attempt at fault finding was to check windows settings and close anything in the background that might cause the PC to cause the spikes. Nothing worked. The pops occur through the audio interface's headphone out and the decks headphone out. I read that possibly it could be the cassettes causing it by having a bit of magnetic charge, so I always fast forward and rewind them a few times and regularly run my head cleaner/demanetizer tape. The only other thing I've read is that it could possibly be down to 'dirty electricity' and other products around the house causing spikes when they switch on? Not sure what else would be kicking in every few minutes though causing it. Or is it just the deck slowly giving up?

Any advice would be great before I just bite the bullet and get a new deck and see if the issue hangs around or is sorted.

Many thanks!