Stick with it. People are different, but the MD1a will work. It took me a while but I did get to 100% and was able to maintain it with once a week sessions.
I use baking soda as well.
As for water in the trays, I made custom trays, its cake. my hand one is shallow with the connector very low in the tray, and the foot tray is a 6-8inch deep large tub since I have large feet and sweat up to my ankles.
For the trays, just go to radio shack and buy the speaker connectors that take banana plugs. The MD1a wires plug in perfectly. They I went to the dollar store and got 2 storage bin trays. Once small shallow for hand, one large for feet.
I drilled a small hole in each for the speaker connector and put a rubber washer on each side just incase. I didn't want a leak.
In total I think it was $7 bucks for 2 finished trays. They have lasted since May 07 so far.
I never checked my Ma rating or what not, but I run at number 7 for 15 minutes each polarity. I do 1 hand and 1 foot, then switch and do other hand/foot. Same side, eg right hand/right foot, then left hand/left foot.
Anything over 7 and it feels like its burning my bones. =)