Put a o-ring around your feedneck to stop the hopper wobble. Or you can put a few pieces of electrical tape right under the whole where the paint feeds. It is called polishing internals.

Here is a how-to from WKS_weiner:

There are two ways to polish the internals of a 98c. one way is to use
steel wool...

it cost about $2. you can find it at any hardware store. but make sure you
get the right kind....

...make sure you get #000. as shown in this pic. you don't wan't to
messup your gun or anything. first step...

take apart your gun. remove all the inernals. then clean up all the gun oil
that is on the left and right receivers..

...when you start polishing the receviers...

....the best place's to start are the, back and front bolt areas, in the area
were the linkage arm moves Around, in the area were the sear moves
around and any other place you feel like. just remember to polish the
same areas on both recivers. also when you use steel wool to polish the
98c i may get alittle messy. so when your done wash off both recerviers
with running water and dry throughly. make sure no left over steel wool is
on both receivers. if there is this will cause major problems. when done
washing and drying put gun back together and you are done.this will help
your 98c in the long run...
the other way is to use a dremel tool. i don't have one yet so if someone
has one please post how to on this thread, thank you. using steel wool is
the cheapest way to polish the internals but not the easiest way. also if
you own an a-5 you can polish your internals also the same way you can
a 98c.

He he. I got to it before he did.

I just polished my internals today and it only cost me $2.50 for the steel wool and about 3 hours of my time to disassemble, polish, reassemble and test my 98c.  And I still have enough wool left to polish my A-5 before this weekend.  But make sure you get the 000 grade wool. 

I'm not sure but maybe someone else could help us out.  Is it okay to use a heavier grade of steel wool at first when polishing the internals?

http://www.tippmann.com/forum/wwf77a/forum_posts.asp?TID=81182&PN=1 - How to Disassemble Your Gun

http://www.tippmann.com/pdfs/manuals/98Custom_Manual.pdf - 98 Custom Owner's Manual

I think the trigger area is the easiest part of my gun. Everything is simple and if you look at your owner's manual, it is not hard at all.

bluemunky42 wrote: disassembling your marker is very easy forensic. first, screw your velocity screw all the way in until it won't go anymore. then, make sure the marker is uncocked, unscrew all 6 screws, and take off the rubber cap on the cocking knob(if you have it). take the 2 screws out the asa adapter and lift the left reciever off. take out all the stuff that comes right out (i.e. trigger+ trigger guard, sear and sear spring, etc.). when all that is out turn it over and unscrew the power tube. (two screws on the right half of the gun. it is probably loctited on, so it will be kind of hard to unscrew them. take that out, and polish. put all the stuff back in after washing and drying completely both recievers, screw your marker together, and there you have it. -edit- PS. make sure you don't over tighten the screws, or it won't cock because it is too tight. 2-2+1/2 spins of the allen key should be good.

I dont think u really need to screw your velocity screw all the way in.

you just have to have it in far enough to not block the left reciever from coming off.