starting issue

wonder if anyone can help, My Jimny 1.3 05 plate, turns over very slow when started. sometimes it starts sometimes not, It sound like ther's not enough power in the battery and its draining I've had the battery checked and thats fine, I've cleaned and added another earthing lead, checked all the fuses to make sure there's no drain, Whats annoying is when I 'attach jump leads from another car it starts first time...
Last Monday it wouldnt start, so got a lift to work, jumped in two days later and bang it starts first time. yesterday went to petrol station filled up, just back in and guess what it didnt start, got a man to help me push it to the side. jumped in 5 mins later and ys you guessed it, it started:evil:
does anyone have an idea whats wrong, it's really annoying me now
thanks
Pauline.

Dodgy earth maybe ?

thats what I though but got someone to fit another earth cable from battery to engine block and its still the same ,,,,,

you 100% about the battery? - strange it starts after being left but was it very very cold when it didnt ?

starter motor connection loose or corroded???? Same symptoms as flat battery, booster battery often
overcomes the resistance.

Bry.D.

ill have to check is it difficult to replace the starter motor connection?