A few examples of telescopes and their restoration. Some images are just of the finished telescope.
The telescope in the display cabinet was done for a school. The telescope was made by Ken Beames, who built the Linden Observatory in the Blue Mountains. It took many hours to bring back to its original condition so that it would no longer deteriorate whilst on display.
What do I dislike the most when it comes to being asked to repair or clean a telescope? Dew damage! If you are going to spend $1,500 or more on a telescope, be sensible, include an amount in your budget for a dew removal system to go with it. Case in point, I had a Takahashi brought in for a front lens clean, the dew spots had been on for a long time and so had the mould. At more than just a couple of thousand dollars for the telescope, another $300 for a heat strap and controller would have saved the $200 cost of removing the objective lens, cleaning them, putting them back in the cell and collimating. Be sensible, prevention is easier than the cure!