(shouldn't they fit the proper spring and sell the pump as correct?)
In an ideal world they would, but sadly most C/C spares suppliers just want to sell us `stuff`, with little regard to quality. The original pumps were made by Holbourne Eaton and were fit for purpose, but I think any NOS were used up a long time ago. The only available new ones now are made by County to a suitable quality apart from the spring, and they seem to take no notice of people informing them that the pump is delivering too high a pressure, that`s where Robsport stepped in.