After rebuilding my 250, it still leaked. Or, I'd better say, leaked agáin..1 of the damperseals had come loose?! So I strongly advise to glue them when rebuilding to avoid this. Be aware to use oil proof glue and glue that doesnt eat the seals!
I sééms ok now, as far as I can tell. Still awaiting results in the 'standing in the cabinet-test' to show any oil leaks.
I does still have that 'rattle'though, when cocking. Like the FWB300 has too, sounds like some antibear trap.
I didnt have the rattle when I first cocked it first shots after rebuilt. However, than I stopped halfway the cockingcycle once to relocate my hand. I héard the antibeartrap kick in. Since than, the rattle's back during cocking..Probably it sticks?? I already had this befóre rebuilding and my previous 1 had it too.