gremlin's in my spark!!!

here's my problem.
i go out one day the duster start's great purr's like it should.
the next day try, no spark just turn's over the battery ran low
hooked cables up let it charge checked connection's all seemed ok
tried again away it went it started ok for the last 6 times went out
today & no spark !!!!
it,s got electronic dist. msd 7al & mallory ignition coil we soldered all connections checked all ground's to & from coil it ran great till lately, would it be something in dist. ? could use your help new at this