i've got a ctd hotpoint tumble dryer with no heat, tested thermostats and found one faulty, only the two replacments i have one says 120a and the other 150a. yet the two removed are identical apart from one has a blue dot. which is which?

i've guessed the blue dot may mean it's the lower rating and it seems to be working ok but would rather make sure it's 100%

any views?