Great site this is, I've found it very helpful.
I'm dealing with a Sony TC-645 tape recorder, I bought it on a garage sale and it was in pretty much good condition.
Heads needs replacement or at least cleaning but sound it's pretty good. Not muddy or dirty.
Lately speed of the tape has slow down considerably although speed of the reels is steady and non fluctuating.
Since here in Mexico this units are pretty much disappeared from the face of the Earth it's impossible to find someone that takes the challenge to diagnose it and repair it. Now that I was able to download the service manual from this site maybe can find some technician that step up to the task.
This thread is to ask you guys, who surely have more experience and expertise what could be causing this issue? It's a capacitor? the belt? as I mentioned before, both of the reels spin at a steady speed, not slowing and regaining pace, so I'm clueless.
Also, the analog number indicator on top of the unit was working fine, but after I opened the front plate to apply compressed air to clean a little the inside and close everything again, that meter indicator it's not working anymore.... What did I mess with?
Hope you can guide me here, when I was a kid my father used to have one of this reel to reel from Zonda (a long gone mexican electronics manufacturer) and I remember I loved the quality of sound these machines deliver.
Help me save my Sony!!