TENS / EMS for Achilles tendonitis rehab?

Two years ago I got Achilles tendonitis in the right leg. It took well over a year to recover and that was following consultations with for various reasons more than one physiotherapist – but the treatment was basically the same, a combination of loading and stretching the ankle. After several months without any sign of progress I went to see a musculoskeletal specialist consultant – whose advice was diametrically the opposite of what I had been given up to then. After several more months the condition seemed to recover.

Earlier this year I experienced what seems to be by all appearances an identical wound in the left leg. This brought me back to the quandary of deciding which of the two approaches to follow. On the advice of a friend I invested in a TENS machine with an additional set of EMS programs. Apparently the latter could be good as a “bridge” between the two approaches above. But whilst I have found out which EMS programs to use, the manufacturer was unwilling to give medical advice himself on the important point regarding the correct placement of the electrodes. I have tried but without success to get such guidance from local NHS physios. The manufacturer suggested that I search on YouTube. I have not yet found a video that focuses on this problem in particular – and of course one has to treat with caution what may turn out to be unqualified advice on YouTube. The machine is therefore still in its box.

Can anyone provide a link to an authoritative source of advice which would tell / show me how to proceed?

Thanks.