Where did my gauge fluid go

[V8guy]

One of last winters projects was the hydrostatic fuel gauge on our 35. I removed the gauge cleaned with acid water then isopropyl alcohol. Removed the sending unit blew cleaned it and blew out al the tubes with compressed air. I also blew out the gauge line while it was disconnected from the tank unit. Filled the gauge with new gauge fluid let it stand over night re checked still on the empty line. reinstalled every thing add 10 gal of fuel gauge was at about 3/4 looks good. worked ok for a few days then the fluid disappeared. Removed the gauge no fluid in it took it apart again looks like the flub burped over the glass tube into the gauge. IDEAS