I was having difficulties with the release of the combined tailgate as described by the forum members and checked out both the upper gate latch and the lower gate latch. By gently removing the plastic cover over the lower gate mechanism, the soft close gear is accessed. I found that dust and grit had accumulated over this mechanism potentially causing a slow release. After giving it a good blow out and clean, I applied several coats of WD 40 which now seems to have cured the issue. Ten days later.... not one failed opening action.
Thanks so much for your forum and for the solid advice from all the members. Alan, South Australia....