125-200cc Power valve return spring - Broken

Hi guys,
Thought we needed to do a top end or just a ring on sons 2010 XC(WR) 150 and on disassembly when I got to the power valve cover a small piece of metal dropped out and I found it was part of the return spring (Husky part # 8000 83109).

Son was complaining that it had lost all bottom end compared to normal but top end was still their.

Bike has only done around 50 hrs so thought it was due for a ring. Compression on our gauge is 90psi compared to my 165 which is only 2 hrs old at 132 psi on my gauge which has a small rubber tube of length 100mm plus adaptors plus gauge.

Best regards,

ohhhhhhhhhhh ooooooooo.
exact thing happened to mine.
felt like it was down on power so i pulled it down to do topend change and found the same spring was broken.
haven't got my bike running back to full power since, i.e. 6 months ago.
good luck.