I went to the Brentwood Coronation event and finished a KONICA VX200 then re-loaded a Fuji Superia 400 - I processed the VX200 -- all BLANK except for the fogged leader so i CUT the Superia 400 and processed == nearly all BLANK except for 4 frames spaced out . I tested camera - the mirror went UP but the SHUTTER was NOT OPENING ! -- I kept trying it out -- put it on 'B' and suddenly it worked -- other speeds worked OK -- I can''t rely it will work all the time . I had a look in Base-Plate - the Magnets were not corroded -- any HELP Please