G4 Titanium 667 (2002) laptop power supply issues, question

Hi all,

Ok, here is a problem that has been frustrating me about my older (but loved) laptop.

I have...
G4 Titanium Laptop, 15", 667mhz computer, made in May 2002, purchased new
I have owned it and its never been dropped or anything
Its out of warranty.
6 months ago, I had the logic board, mother board replaced by apple
I recently upgraded the HD to an Hitachi 5400 mhz 100 gig drive
I am using a newly purchases apple battery (i know, they stopped manufacting new batteries for this powerbook).

For the past months, my laptop is having issues with power as far as I can tell...
When I press the 'power' button, nothing happens... or, the keyboard has power (caps lock, number lock, etc) but the computer does not boot - no "BONG" or CD/DVD drive engauging.

If I drain the battery a bit, and charge it for a bit, about 5 minutes, then it boots normally.
Sometimes, I must alternate between AC power and battery, and sometimes it takes many attempts, etc to get it working. Also, if i change the angle of the computer, it sometimes boots on the first trip - 45 degrees, etc.

When it does work, sometimes the computer just boots to a gray screen... hangs there. Or, boots, then freezes (no mouse or keyboard use) - like the power is cut, but the computer is on.
Also, sometimes the crashes are so hard that it resets the clock to 1969 then next time it reboots. But, after several attempts like this, then the computer runs fine. Weird!

I thought it was the HD... I thought the logic board replacement 6 months ago, might have solved it... Now its almost worse.

THe actions i have taken:
- I have asked APPLE STORE if there are any known issues with bad power key or something like that... they said no.
- I have tried resetting the P-RAM and those boot tricks, does not help.
- I have tried resetting the clock - the small switch under the keyboard, this works, but re-sets the clock, and does not solve the problem of not booting.

So, wondering if anyone has any advice...
- If i should by (and install myself?) a new power supply, or leave it to my 3rd party repair center used (out of apple warranty)
- Or, should i cut my losses and save up for a new laptop..... although its 2002, i refuse to believe i should have to write this one off.

Let me know your thoughts, etc.

Best & thanks in advance,
- Justin
justin@wanpela.com