Earlier on, h1982 gave a good tip for deducing the letters. To paraphrase - the removed word pairs must be of equal length each time because they are 'middle-less' (discovering the missing middle letter will produce a single word each time).
Then you must have missed h1982's post too, lumen - I merely paraphrased it (or is it my response to your request for a hint to 37a that's the 'spoiler'?)
It's all fine drxx...I didn't follow H1982's gentle hint, as I was sure it couldn't work for 9d or 26a. But later I happily realised it could.
Then I saw you had made it very explicit at #45 and 46.