If you search the Cherubini Hunters forum with the words "diesel tank" you will get about 30 hits, all dealing with the issues. Most of us have put one or more clean-out hatches in the tank and physically mopped out the grunge. Fuel polishing equipment is also a partial fix. The tank is easily accessed on most H37Cs by removing the wood base of the quarter berth. On some of the older boats the tank is under the cockpit sole and I believe it can be removed through the starboard cockpit locker. Although aluminum diesel tanks last a long time, check the interior for pitting an corrosion that could develop into leaks in the future.