Hi Martin,
You do not mention what model no ALKO stabiliser you have.
reason for asking I have the 1300 model having like you changed from a bulldog leaf spring type stabiliser because it came to hard for me push down the locking handle.
After several trips with the new stabileser fitted I had to visit my local dealer for a service , upon hitching up the mechanic told me that I was not locking the alko correctly, what i was doing was pushing the lever down before i had turned the locking wheel untill I felt resistance,now after turning the wheel and then pushing the locking handle down I do feel the resistance, not as much as the old leaf spring type.
What it did prove was that I had been towing the van for 6 months , one of the trips on the A66 from Scotch Corner towards the Lakes with some gusty winds, without the slightest wobble,
so without the stabiliser the van handled very well.
I do use the stabiliser for peace of mind the extra large continental lorries that wiss past me , I never feel anyside wind suction.
Royston