Apologies if this is a bit of a newbie question. But I thought it
might be easier to _find_ pros in rec.audio.pro than elsewhere.

I have, for a couple of years, been mucking about with a decidedly
entry-level Tascam MF-P01 Portastudio, which is to say, their least
expensive product. That being said, recently I've found that it does
not produce sound during playback on any of the four tracks - even
though there is amp hiss and sound from the microphone when I turn up
the volume, so it's not a problem with the headphone jacks.
Furtheremore, recording works fine on all four tracks, as I play the
results back on other decks and notice no degradation in quality.

This machine is about four years old but has only seen about eighteen
months of sustained - if infrequent - use.

So why isn't it playing? Is it related to this 'head-life' phenomenon
I've read about in incomprehensible terms? Is there anything I can do
without taking it in for service to fix this problem?

- And be sure to vote on 2nd November! -

I seriously doubt it's the heads, if you are hearing a microphone you must
be in record mode, there is a manual on line - are you using the 2 RCA outs
for the playback? Unplug the phones when you're trying to play back...

link to manual:

http://www.tascam.com/Products/MF-PO1/CopyMFP01En.pdf

Did you clean the playback head at any time? Maybe it's built up with crud
which would lead to signal loss. Be careful if/when you decide to do this
- I'd start with a Q-tip and deionized water (better yet follow the
directions in the manual).