Battery earth

Hi all swapped my battery earth lead the other day because the original looked gammy and untidy (I was very bored and couldn't find anything else to do) anyway after a day I notice it didnt start as quick as it use to I left to see if it was just me imagining things then the day after I come to it and it wont start at all but when I checked the battery it was fully charged anyway long story short I put the old earth lead back on and it fires up straight away anyone any ideas ?

A better connection at both ends than before, what else do u think it could be?

just strange as I used brand new connecters and used the same earth point even cleaned it up to make sure it had a good connection

Fault cable maybe if it was pre-manufactured, refit and see what happens or compare the resistance of both.