You will need to service your fuel system in several reasons:
Please, follow all steps
1) Find blue plastic pipe for diesel drain and place it to any bucket to collect liquids, open end of blue pipe must be below level of diesel filter
2) Open valve for diesel drain
3) Drain all diesel from diesel tank
4) Start filling diesel tank from top with 0.5G of gasoline collecting it in the bucket (1)
5) Check diesel tank condition after cleaning from top with gasoline flashing
6) If Tank is clean, flash it again but with NEW diesel now, if it is not clean flash again with gasoline
After these two (or more) flashes your fuel system is clean and empty, and you can replace you Diesel filter.
7) Remove old plastic cover part of Diesel filter, inner metall mesh and o-rings.
8) Clean metall part with paper towel.
9) Install new inner part for diesel with o-rings
10) Instal plastic part of diesel filter
11) Start filling diesel tank with diesel
12) Clean or replace burner brass nozzle
13) Start machine
14) Adjust burner