The side stand spring is strong isn’t it? It has to be or it would stretch when you use the stand.
There is a tip which might be useful to others and we are going to put it into our assembly instructions.
Get a length of strong cord. Place the bike on its centre stand. Make a loop in one end and put that into the top of the spring. Next wind the other end of the cord round the pedal spindle. With the loose end of the cord firmly held and the pedal at the top turn the pedal and the spring will be stretched. When the top of the spring is in line with its top anchorage point press it into line and gently release the tension. This procedure is easier if done by two people.