Korg Poly800/EX800 Users

this one must have been dealt with before:

i just just got back to my ex800 after a long time. 
it is still unmodded, and the battery clip i'd installed 
instead of the original soldered battery had come undone, 
so no patches, and the usual slow-rise noise with delayed 
vcf LFO patch(...). but my buttons are fer sh*t: 5 almost 
doesn't work at all, 3 is dodgy...well, they're all in a 
pretty rough state, makes progging a nightmare.

so, what is the info on this? must i remove that board and 
somehow open up the switches and clean them? i'd like to sort 
this out before i attack the mod.

2nd question/issue is something i have wondered about for a 
long time: the difference between the pulse wave and the saw: 
on my 800, the 'saw' sounds almost the same ('square-ish'), 
just louder. i wouldn't say either is distinctively square 
or saw...kinda in the square department more, and i'm not 
really hearing a distinctive 'saw/ramp'. is this normal?

number 3 is: could somehow explain, or do a sketch for me, 
of wha exactly the envelope terms 'slope' and 'breakpoint' 
mean?(ok, so i was mucking around with it with the VCF EG 
inverted, and that didn't help clarify much- again, the default 
noise patch)...pathetic, really, when i've had this thing for???
well over 15 years.