right like kully says ive got the same problem,there is two places to spray,
the first is where the cable goes goes into the bulk head you cant miss it just get your head down into the feet well and you will see it.
the second i will have to get back to you on it due to i need to look under the bonnet and i havent got my car on me,the GF has it.
it cured it the first time around for me but i thought it might come back so i had a new cable fitted by the stealers,was fine for a few months but its back again but no real problem just got to spray some wd40 or similar on it.
like you say al it seems to be worse when the car is warm.
hope this helps for now.