Front Speakers Don't Work - 94 Accord

I have a 94 Accord, neither of the front speakers work anymore. The
first sign of a problem was they would cut in and out intermittently,
but now they don't work at all.

Thinking it was probably the head unit, I bought a replacement OEM unit
off ebay for a few dollars. Still no joy.

I'm a novice at this, but now suspect the wiring harness and/or the
wires for the front speakers all gotten pinched somewhere ... or is
there something else?

My question is, how would I test to see where the problem is?

>From what I've read I don't want to mess with the wiring harness to the
radio, so I'm wondering if there's anything I can do even if I do find
the problem (???).

Thanks for any ideas!