[sdiy] advice please -- aging chips and caps

[john mahoney]

Having read Scott Rider's article "Things to Know When Repairing Vintage
Synthesizers"  (http://www.oldcrows.net/~oldcrow/synth/tips.txt), I am now a
little concerned about my Korg Mono/Poly, which has reached adulthood
(assuming that synth years = human years). Basically, Scott says to replace
all old 4000 series CMOS chips as well as certain types of caps.

My questions for you folks:
(1) Many of you have years of experience. Have you seen signs of CMOS
senility or caps with Alzheimer's?
(2) Should I replace the "at risk" components now, even though the synth is
working perfectly? Or, wait and see, but *if* something goes bad then
replace everything as he suggests. I'd like to add a few extra
inputs/outputs/patchpoints to the Korg, so I have reason to do surgery.
(See? This is a DIY question!)
(3) Given the parts list below, do you see any parts that I should try to
obtain now, just in case? For example, if the SSM chips are available,
should I stock some? (I don't even know if the SSM chips are available
anymore!)
(4) Oh, yeah: What's the difference between the HD14000 series and the
normal 4000 series, if any?

ICs in the Mono/Poly (thanks to the excellent Zen Mono/Poly website):
    SSM2044 4-pole voltage controlled filter
    SSM2033 Voltage controlled oscillator (Qty: 4)
    MM5837 Digital noise source
    Intel 8049 8mhz CPU
    HD14007UBP Dual complementary pair + inverter
    HD14013BP Dual D flip-flop
    HD14042BP Quad latch
    HD14066BP Analog CMOS switch
    HD14069UBP Hex inverter
    HD14071 Quad "or" gate
    HD14174BP Hex flip-flop
    MC14504 Hex level shifter
    NJM4556 Dual high-current op-amp
    NJM4558DV Dual op-amp
    M5230L Variable output voltage regulator
    TL072 Dual J-FET operational amplifier

Thanks to everyone for any and all insight you can offer.
--
john