Unless you calibrate your deck very well,dbx will exaggerate all of it's bad qualities, kind of like me and alcohol. Speaking of which, don't use rubbing alcohol on your deck, it's got a goodly amount of water in it. I use 91% from the drugstore on mine, and haven't had problems yet.
My method of adjusting decks may well be wrong, although it seems to work ok, so I won't give advice here, but I will say that you can get oscilliscopes and tone generators on ebay for absurdly low prices if you look for them. The fine folks on this forum have gone into great depth about how to properly calibrate your deck, easily found with the search function.
Oiling motors can do more harm than good..some have internal lubrication that will be dried up by the wrong lubes, especially WD-40. Best to use a lithium grease VERY sparingly if you are bound and determined to go this route, I use an insulin syringe with the needle broken off myself, and no more than 2 units according to it's measurement...I may be doing bad things here, but it has worked for me.
Hope this is of service to ya!