goiterjoe: How much water is "a small amount"? How much HgCl2 do you use per gram of aluminum? What is the scale of your reaction?
Have you actually filtered off the sludge w/o basifying first? It is a BITCH! By basifying the reaction, you are converting the aluminum hydroxide/methoxide into NaAl(OH)4 which becomes a small black blob on the bottom of the flask. Filtering takes about 5 minutes. You must add the base correctly, though, or you will not get this awesome precipitation. Here is how I do it:
After the rxn is done (it is not necessay to let is cool down first), add exactly 500g of 25% NaOH to the rxn while stirring the reaction at maximum speed. This addition should take between one and two minutes. You don't need to drip it in, but you don't want to dump it in all at once or your rxn mixture will become the consistancy of clay and will require lots of extra base/solvent to salvage. After the rxn stirs for a few minutes, the fine particles of aluminum will begin to coagulate while a good deal of MeAm gas is evolved. One the gas stops coming off and making the aluminum float, give the flask a good shake and all of the aluminum will sink to the bottom, leaving crystal clear solvent on top. If you let is sit overnight at this point without stirring, the aluminum will collect into a golf ball sized black blob that is stuck to the bottom of the flask and you can simply decant the solvent without even having to filter it. Then just strip off the methanol and perform an A/B, distill the freebase, and gas. The above method is for 30g ketone, 24g MeNO2, and 33.5g Al. If your numbers are different, you may require a different amount of base.