If the Injector is removed you can replace what I call the Nozzle Nut. That won't change the Pop Pressure. However, taking that nut off it is easy to get dirt inside.

It won't become a air leak because the pressure inside when the fuel is injected is greater then the pressure outside.

If it was mine I would simply leave it alone and keep and eye on it and aquire the parts to fix it.

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84 300D, 82 Volvo 244Gl Diesel