Be careful about replacing the springs with stronger ones, this has the effect of making the main gear legs longer. This gives the jet a negative angle of attack
I used the Tygon fix on mine & the next take off was a real scare. The jet just would not lift off the runway. Just as the end of the runway approached, full up elevator saved the day & it jumped into the air.
I quickly removed the Tygon.
If you replace the springs, consider lengthening the nose leg.