We had a leak in one water tank and after pulling the tank and having it welded we ended up having two leaks!
To solve the problem, I plugged all holes in the tank (vent, inlet, etc.) connected a dingy air pump, and slightly pressurized the tank. With soapy water I checked the tank for leaks and marked them. Then, after cleaning the area around the leaks, I pulled a vacuum on the tank with the air pump while I applied epoxy to the leak areas. The vacuum pulled the epoxy into the tiny holes. I also applied heat to the area to thin the epoxy and later help set it. When the epoxy was pulled into the hole, more was applied I kept doing this until the hole was plugged with epoxy. Twelve years later and no leaks.
Burt Preston
H44 -83
Exuberant

Hi Joel,

I dont know about Grunnert but I just replaced my Seafrost compressor with another Seafrost compressor.  I did this to save the plates and simplify the installation.  Seafrost consumes about 40 amps, for about 2 hours per day.  Not too bad on power consumption.

Dual air cooled  compressors are probably a better option if starting from scratch and unlimited funds.  Even the simplest fix requires time and tools and skills, but it

When we got our 49, it became clear to me that I wasn't going to figure out the Gunnert and I believe they were complicit in murdering our batteries.  So, shortly after we got our 49 we replaced the Gunnert with a pair of Frigoboat units, one for the freezer and one for the refrigerator.  They both fit under the hanging locker in the aft berth, starboard side, and a pair of keel coolers fit under the seat in the aft berth.  We put a grill in the bottom of the cabinet so they can get air.  We got the option that allows us to switch to air cooling, like a home refrigerator, so we can use the refrigerator and freezer while on the hard.  I haven't had to touch the Frigoboats since we put them in about 8 years ago.  They do have a complicated control unit and I can barely figure out how to adjust the temperature. 

Jack
H49#31
Moonlight

There are also rebuild kits available for about $160.  Often you can take apart the pump, clean out the crud and reassemble and it will work fine.

I would try the Johnson spx flow f5b-19.
Jim 46-53