Very interesting, I’ve worked on a number of these decks over the years and I’ve never run across one with that little playback amp in the mechanical section. They made so many variations on this deck while keeping the same 4010S model number so I guess one really has to go by the amplifier model number.

That's late '60s and the early revision with PNP germanium transistors. Later revisions don't have the same transistors or the playback amplifier inside the deck. The two upper micro switches behind the faceplate are also gone on later ones, as well as the patch cables in the rear.

Damn I wish KZread were around back when my pops threw his Teac exactly like that one away because he couldn't keep it running anymore. I would have held onto it for sure if is known he as getting rid of it. So many memories of when I was little hearing that thing kick on on Sunday mornings while mom cleaned the house singing along with the Beatles blaring thru the big wood cabinet speakers with wooden grilles on the fronts. Those things were LOUD for back then. I Still smell lemon Pledge when I see one of these things... Still remember specific reels he used that he'd recorded off of the armed forces radio when we lived over seas after he came back from Vietnam. Oh btw, im pretty sure every original owner of those units was. a smoker back on the day. Lol!

It appears to have a mechanical relay to switch heads for the reverse direction. If the relay is noisey, that could also be part of the problem. Rapidly switching direction might help.

i have worked on a few Teacs. You have the left side threaded wrong. There is also a allen key on the reel tables buried behind to set reel table height.

I removed the reel table to install the counter belt, it was not hard.

I watched your video at a perfect time as I started restoring a 4010S that I inherited from a family member. Mine had many of the same issues yours did including the noisy output. Unfortunately, your video was a CLIFFHANGER when it came to the replacement of the transistors. Would you mind telling me if the NTE102 were a directly replacement for the 2SB486 on the preamp board, and if so, how did the unit sound after you made the replacement? I wish you’d do a part 2 to your video!

Thank you for sharing your work! I am on the path right now with a unit I'm trying to fix for a friend. Your schematic looks quite clean and readable - would you be willing to post it here? The PDF's I've found are badly compressed and some part values are compressed into blurry blobs of pixels... Thanks!

where did you get your repair Manuel? I have a copy of it that I got off the internet, but your looks like an original and is larger and easier to read. - Sorry, I read a bit further down and saw the same question. Whould it be possible for you to email to me also?

Hi, i recently acquired a teac a4010s (ar40s). Previous owner kept it in a closet for decades. It does not have the 2 silver screws on top of the cabinet like yours, do you know what year it was made? i Change both belts, lube and deoxit. Every lights and meters working. Sounds really good. Do i need to replace the capacitors? its working and sound great thanks.