Man why u still workin (or trying to anyway) on that remix? a buddy (Trance producer) of mine used to strugghle like you for months on different "remixes" and finally i coaxed him to stop doing re-mixes and concentrate on his own original tracks - he has, (after 6 months
) and is way happier with his own work now.
I suppose youve tried this but in case you havent last couple of suggestions i can give yeh;
1, start a new "project" with said marimba and use every fx available to you to reproduce the sound ALL BY ITSELF with nothin else cluttering up ur ears . ( and try pairing it with another preset if that doesn't work) when you get it close as damn it bounce it out and slap it into ur remix.
2, download Kilohearts essentials FX bundle. any amount of fx for free and doesn't use an iLOK ( with a sign up).
3, If you havent got these already download them also free, UVI WORKSTATION (i think it downloads an iLok with it but you can alway delete the fucker after youve installed it. some cool presets on it. SYNTHMASTER PLAYER, is another one with loadsa cool presets too.
go onto W.a prod site and download the free "daily producers tips" PDF theres 2 on it, vol 1&2.
if all else fails delete ur remix and find somethin more easier - theres always a solution man, although you may not like it. but if its giving you that much grief either delete it and move on and maybe ( i wouldnt bother me hole tho' if its annoying me that much) go back to it as ur experience broadens.
my motto is: if its giving u grief, kick it, bin it or feed it to the dogs.
good luck!!!