Any suggestions of how to repair wood on the inside of window frames (house near beach also very dated)
Welcome to the Bunnings Workshop community @alexro. It's terrific to have you join us, and many thanks for your question about repairing window frames.
You've obviously seen some moisture damage to the timber. Has that water penetration issue been resolved? If it has, then the timber can be sanded back to improve the look and remove and decayed areas. You'll then be able to apply a varnish to restore the colouring and protect the timber.
If, once sanded, the damage appears to be substantial, then you could use a timber filler and paint the frames to refresh their looks.Please let me know if you have any questions.Mitchell