Found my old thread as I had a failing strut after only 16 months with not that much use.
The strut has been rattling when driving and hardly working when popped, even when not that cold.
Anyway, before I bin the mod I got two new (pattern) struts off ebay for £15.50 delivered, just put them on and it worked first time, even withoiut me 'pumping' the tailgate and my car is also on a decline with the temp about 2-3C here today.
They are marked 600N, but I'll see how long they are usable for. Being brand new I'd expect them to pop every time anyway.