Here's the list as it existed in 2000: http://www.sk8stuff.com/f_rules/isu_...deductions.htm
There's no difference specified between falling on the first jump of the combo and then doing the second jump vs. falling on the first jump and not doing the second jump. In practice judges may have considered the difficulty and quality of the second jump, not to mention its actual existence, in setting their base marks, but leaving it out doesn't seem to have been a mandatory deduction.
I think that in 1992 the deduction for falling on the first jump, or on a solo jump or spin, was 0.5, lowered to 0.4 ca. 1994.