The things i've removed from my 130, aluminum to aluminum seemed ok with a little pb blaster and small amount of heat and not overdoing it, it's when you get aluminum with some kind of crappy metal bolt like the water jacket bolts or any of the other dressing bolts i've not been able to get apart 1/2 the time, they sieze up real good or like the swivel tube with the swivel in it, tube is alum, swivel is some steel and pressed in, that ain't ever coming apart in salt water and i've had several dealers say they don't replace just the rod they have to replace the swivel with the pressed on piece as they have to destroy the pressed on piece to get the swivel out. (i considered replacing that when it was apart but being it's only visual and there was plenty of meat left so I just cleaned it up).
It looks like these, the original part number is what john pasted above but looks like these are the alternative part nums from checking a few sites:
http://www.boats.net/parts/detail/honda/H-07SPA-ZW1020A.html
http://www.boats.net/parts/detail/honda/H-07SPA-ZW1010A.html
Manual suggest putting it in a vise, then using the spanners above, i'd pb blaster it for a few days, tighten a small bit then try to loosen, last resort gentle heat.
I've not messed with these but looking at the manual and diagrams they don't look all that complicated. You have the shell, pistons, seals bunch of orings, then the reservoir and the pump, everything look easy enough to disassemble and clean assuming you can get the caps off of a salt water one....of course famous last words =)
Though from examining the shop manual there's quite a few assembly steps and tips, I wouldn't want to do it without it. If one was taking it apart, i'd disassemble the whole thing clean everything, replace all the o rings in the pump,etc while you're there all of those are typically cheap stuff orings,etc.
According to the manual yes the cap seats against the oring, but on the top of the cap there is a recessed area with a dust cap and oil ring, I wonder if those are replaceable without removing the cap, seems like you could press em in somehow but i dunno..
Keep me updated on yours if you do decide to give a diy a try, i'd buy the tools off you if you get to your's before me mine or visa versa, or could always ebay them i'd imagine for a few bucks to offset the try.
I haven't checked any dealers though on what they'd charge or anything or used units but worth doing that.
