renault 1.9 dci help

[renholt]

got a renault 1.9 dci 52 plate it would not start , and after being on computer and the live data chcked for rail the pressure and an injector test and no faults found compression tested it and found cylinders 1+4 no compression .head was removed and recoditioned by an engine recon place req facing valves and seats recut .no signs of piston or bore damaged so head replaced with new gkts and belt still not starting and compresion low on cyl 1+4 any ideas all i can think is rings but no signs of damage ,could they be gummed up?