I grew up around RtR decks, my brother had one (2-track 3.75/7.5 ips A77, 1971) he brought back from ‘nam (via Heidelberg Audio Club) which I inherited along with a boxload of recordings. Deck was working until I picked it up, set it down, and one of the aged, fragile trimpots - speed control one - broke and I went down the refurbishment/rebuild trail with the help of Peter Mony at Nagravox, Australia.
Deck worked incredibly well, then I found another, cheap, 4-track 3.75/7.5 and rebuilt THAT.
I’ve “worked with” John French in replacing heads - he’s one of if not THE best person for refurbishing and/or mounting/aligning them.
Then I found a handful of B77 decks, including a 7.5/15ips 2 track I rebuilt, recalibrated and sold to a studio. Then I did the same with one PR99 Mk3.
Along the way I kept a B77 4-track 3.75/7.5 and a PR99 Mk3 (2-track, same speed) and am in the process up updating the PR99.
All told, I’ve done all electromechanical “stuff” (recapping, replacing trim pots, cleaning connectors, rebuilding brakes, adjusting pinch roller pressure even going so far as to learn how to glass bead-blast the spindle) on a dozen decks including installing new boards from Revox (now Premium Hi-Fi) as well as from Audvance Audio. It keeps me busy and I still play the tapes my brother made and have put several of my LP’s on them, bought some prerecorded tapes (the Angel series classical are some of the best audio I’ve ever heard).
When a tech tells you a basic calibration/cleaning will cost around $600 and up, it’s worth every penny. I can tell you I probably, as an amateur, put in around 100 hours in overhauling one deck. I had a receipt from one guy showing he spent around $1200 to have an B77 4-track rebuilt around 2015 every hour, part was detailed in the invoice. He bought the deck NEW for that much money about a dozen years earlier (my numbers may not be exact but they’re close enough).
I rebuilt all, again, with one exception, with the backing of Nagravox. I did ONE 4-track B77 on my own, sourcing parts, learning about types of bearings, more electronics than I ever did in HS in the early-mid 1970’s and as a hobby, while it is not a money maker, I’ve managed to break even to the point I’ve kept the 2 decks I’ve got. Peter Mony’s kits are the BEST,
That said… depending on what you want one for, there are a boatload of scammers out there, you can do a deep dive like I have or keep your eyes open on the USAudioMart, ePay and Fakebook marketplace and local audio sellers but you need to have a tech around to at least run the deck through its paces and check the calibration and alignment before you really get into playing/recording with an unknown quantity.
Interestingly, Revox is NOW producing a B77 Mk3 and it’s priced somewhere over Ten grand, IIRC. I’ve seen some of the upgraded models of the PR99 (out of Switzerland, seller I forger the name of offhand) for upwards of $20k.
This is the most expensive way of playing music around - short of hiring a string ensemble, full orchestra or supergroup band for a bar mitzvah yourself.
You can probably get a “decent” working deck now for anywhere from 1-2k,
Find a place that sells them, go listen to them. Bring some LPs to compare. then listen do digital, streaming. For high-quality audio, I’m hard-pressed to say LPs sound as good - GENERALLY (there are SO many variables involved), but for something like ELP’s first album, I have it on CD, LP (original and later reissues) and 7.5 IPS audiotape (original) and I (and my musician son) find the tape sounds MUCH better.
Just my 35 cents (that’s the original 2 cents plus Bidenflation).

