from the sounds of it you have a duff oring in your lpr, fairly simple to fix if you know which seal it is, more than likely its the tiny little one in the middle, (so small you usually have to use a pick to get it out!)
the 3 way is not a prob, you just need a length of low pressure hose so you can cut it to the right length for your marker....pm me your address and ill send ya a foot,
for the oring, you are gonna need a cocker seal pack, or go along to your local store and ask them to look at it....last one i changed i think jack at planet charged me 20p! and took me about 20 mins to do, dont even need to take the lpr off the marker