98 Gs300 Cd Changer Problems

[greengsinnj]

Just bought a 98 GS300 and have upgraded wheels & tires and am now onto the audio. Prior owner had an aftermarket system all 'round and put back some of the OEM components before trading in. So, this is what I have:

OEM headunit with LCD issue (no backlight).... I have located the supplier of that part.

CD Changer I bought on eBay

missing amp (at least I think its missing because I cannot find it in the glovebox area)

missing subwoofer

THe CD Changer I bought on eBay was missing one of the mounting brackets (leftside) [anyone have one they could spare??] and rightside brackets sparked when i mounted the unit -- are the brackets integral to electical source for unit?

The headunit doesnt recognize the CD Changer (except for one split-second moment where it gave a ERR300 message) and the CD changer seems to have power but only to shuffle a disc in/out of the play rotation....but will not eject the magazine.

Any ideas as to how to resolve CD changer problem? (seller assures me it was working just fine when he took it out of his GS300 a couple weeks ago)

Any suggestions on what to do about missing Amp? (I have a couple amps that I could mount in the trunk I guess--I bought a 10" 300 Watt aftermarket (kicker) subwoofer that may need more than stock amp anyway?)

Thanks in advance!