I was charging my airplane last night and found that the Magnum 91 FS had no compression.... Found that one valve spring on the rocker arm was stuck... touched it gently with a small screwdriver and it popped into place... What caused that to happen...? I flew it two weeks ago with no problems.... It has about one gallon of fuel through it and the valves have never been adjusted.... I do not have a metric feeler gauge but the gap seemed excessive... I have set the gap at .006 (not metric) and am planning on running it soon... The manual ask for an adjustment of .04 mm... How does that relate to non metric feeler gauge? Thanks..