when i my epic prelabour/labour with DD i kept the TENS machine on for days but found it really annoying if i turned it up past the minimum. The midwife later told me i probably wasn't getting any benefit from it because of that.
My yoga teacher recommends having it on for a short time every day from about 38 weeks so you can get use to it and then it will be more effective. Can anyone confirm that this is worth the bother?
I think you need to make sure you put the pads in the right place - ideally they should be at the top and bottom of a muscle so you might need to get an anatomy book out and get someone to help you place them. Did you have a boost button? I found that hitting that just as a contraction was starting really helped - although I think it was the psychological feeling that I had control IYSWIM?
I'd say definitely try it out by placing the pads in different positions a few times and also have a go with the controls putting it up to the highest you can manage. Did you start the tens as soon as you had the first contraction? Apparently it will only work if you do this. If it's still not feeling right then maybe give it a miss this time and try something else like an alternative therapy?