1. Uranus - Puck: This is one of the most popular spots to farm Gauss because it's a survival mission with a good chance to get Gauss parts as rewards for completing rotations.
2. Void - Marduk: This is another survival mission that can drop Gauss parts, but it's a bit more challenging than Puck because it's an Orokin Void mission.
3. Railjack missions: You can also farm Gauss parts by completing railjack missions, especially those that involve fighting Grineer forces. The Kuva Lich missions are also a good option, as they often drop warframe parts.
4. Arbitrations: These are endgame missions that require players to have completed every node in the star chart. They offer higher level enemies and better rewards, including a chance to acquire Gauss parts.
5. Syndicate offerings: Some syndicates offer Gauss parts as rewards for completing their missions or leveling up your standing with them.
6. Trading: If you're struggling to acquire Gauss parts through farming or other methods, you can always try trading with other players who have the parts you need. However, make sure to double-check prices and only trade with reputable players to avoid getting scammed.