If the front element wobbles and it's firmly threaded into the shutter body, that doesn't sound too good! This could mean that the two halves of the shutter have loosened by themselves, or the shutter has possibly had an accident causing the screws to loosen. Or due to an accident something was bent and binding inside and the fix was to loosen the shutter... If just the timing ring wobbles the fix could be simply to tighten the ring that holds it on, although this is another indication that the shutter may have been taken apart... I'd be sending it back unless you got it cheap enough to take a risk on it.