I've seen about a dozen systems this year that had problems with the vale not opening. These systems are all 410 and are a mix of equipment. On some I simply opened them manually. One system I replaced the LLSV, but found nothing wrong with the old valve. Another Tech at the shop also recently repacled a valve. The valve that I swoped out was a Sporlan ME14S250, MOPD 300, MRP 500, MKC-2 coil.