I'd certainly go for sealing tricks first and leave doing the box seals till the summer!
Removing the drop arm is a bar steward and I ended up paying the garage a tenner to get it off, after trying pullers, heat, violence, etc. Having got it off I couldn't get the ball joint top cone out as it was so corroded so I ended up with a new drop arm (EBay - 99p!) and so I could have used plan B (the angle grinder) and saved the tenner.
Good luck!