We've just replaced ours, which was eleven years old - and we reckon had done 55,000 towed miles - and it's surprising just how worn the inner moving parts were. It was the older type of Alko hitch, which was becoming very difficult to unhitch. It had a button which indicated when you were properly hitched up and passed the 'ForestGump' test. However, a couple of years ago OH couldn't get the hitchlock back on at the end of our journey back from France, and discovered that one of the bolts holding the hitch to the caravan chassis had sheared right through. It had been held on, in transit, because we travel with the hitchlock on (I know, I know, but it probably saved our van and perhaps lives in that instance). The other bolt was showing bad 'wear' in the middle, too, but hadn't sheared. We just replaced the bolts at the time, but worried thereafter that other parts of the hitch were equally worn, and decided to replace the whole thing. Our caravan dealer (friendly) said that they had never seen anything like it, and we were minded to write to Alko, but lost the photographs we'd taken of the bolts, so never got around to it.
We've replaced it with an ALKO 3004, which came in a triple pack including hitch, hitch-lock, and new towball. It had all the parts required to do the job, new gaiter, bolts, etc, and simple fitting instructions. OH fitted it this weekend, quite a simple job he said, and it now looks very smart and we feel that it's much safer too.
See the other post ALKO 3004 v Q200...........