I need some help with a diagnostic issue for a camshaft seal leak. I've had the camshaft seals replaced and the one near the passenger side nearest the firewall continues to leak on the belt side despite new parts. The other 3 are fine??. Shop took it apart and replaced the seal again (yes a chore) - still leaks?? is this a potential bearing issue? does the camshaft need balancing? and if so can it be done? what else can it be?