7,500 is what’s recommended by HK. If you tried to move your extractor (not spring) and it feels solid, probably another issue. You can also break down your BCG and place a round on the bolt head and check for “grip”. You can also remove your spring and see if it’s bent or has any marks on it. Sometime you can bend it back into place and keep using it for a while longer. Also: Check mags, check ejector level, check bolt gap.