I had this same problem. It was resolved by swapping out my headphones. I suspect the jack in the replacment component is slighly out of spec in terms of proper contact alignment as the headphones otherwise worked consistently and could be made to put sound in the left or right by sliding the contact in and out. Also, at all times, there was dimished sound in the "other" ear.
On reassembly, I found there was no need to replace the tape as all the components assemble nicely. I elected to not replace the tapoe also to eliminate one more possible source of annoyance should I need to make another repair in the future.
On reassembly, the hold switch can be a bit troublesome to snap in. I managed to get it in, after a few tries, by tilting the switch down and into the slot, then sliding it into the correct position left-to-right, before rotating it down into the final position. Once it is in place, replacing the left screw (attached to side of case) seems unnecessary as it snaps into place securely and the screw to the top of the case provides a secure hold.
Two aditional recommendations regarding this step:
1) Going forward, if the ribbon cable for the hold switch is torn or damaged, the ipod should (and in my case did) continue to function, although with hold off at all times. If you do tear the cable and can wait, I recommend not reassembling before replacing the ribbon cable to avoid the risk of accidentally powering on the ipod while separating it for the cable replacement. I managed to use it for a while until the replacement cable arrived, but had to be very careful not to accidentally turn the unit on as the hold switch was no longer connected.
2) When replacing the battery, it sits securely without the adhesive. When making the swap, I recommend not using the adhesive. My replacement came with a peel-off backing which I left intact. This makes future operations (like replacing the headphone jack and hold switch cable) much easier.
I, too, broke the hold ribbon cable. I didn't read carefully enough and understand exactly where the cable was under the battery so I clipped it with the plastic tool, then finished tearing it when the battery finally came out.
It would be helpful to identify the location of the hold cable under the battery - I didn't realize where it was located and that I would hit it as I tried to work the battery free. All the information is there in the step, but emphasis could be added.
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