hi all,took the rs out at the weekend for a spin,after a bit of fun it started to rattle/tap from the top end then went quiet,decided to take rocker off to check valve clearences and found that it has hydraulic ones fitted so why the noise?its been stood quite a while b4 i bought it and it had an oil change in october so what should i do,i have another engine with solid tappets,is it worth changing them or shall i leave the hydraulic ones in,cheers.