An ETA 2824-2 should be able to take at least 40 turns for a full wind, so there's definitely something up with your mainspring, given your other symptoms.
I'd recommend contacting Duncan Potter at Genesis Watchmaking service@genesiswatchmaking.co.uk for pricing and availability. As an indication back in 2018 he regulated the 2824-2 in my Steinhart OVM and resealed it for £50. On timing it yesterday it was still running brilliantly. I think his full service is in the region of £200 but do check.