I posted a request for 33/1 detailing parts, but there is not a great deal out there. The only issue I had with my 33 was a split gear, which Howes replaced within a couple of days FOC. (Not a very common problem on the 33s, but if needed, check the reply to my request for replacing the gear.) Once repaired, the 33 runs beautifully.
If fitting the snow ploughs, you will need to cut back a couple of the hoses.
If you are going for DCC, installing the XL decoder is a 15 minute job, but if you want to be able to turn off the rear lights while pulling a train, you have to programme this yourself. The speaker fits perfectly in to the fuel tank. (Maybe that is why they are slightly wide?)
I did not bother with the fan in the end, as it was either too fast and loud, or would not run, you cant really see it anyway.
I have a Howes decoder, and although it's ok, if I were buying another, I would check out the XL decoders that Legomanbiffo produces. (Strange name, but listen to his sound programmes on YouTube) Once the 31 arrives, I will be installing one of his.
I have several of the Heljan diesels, and I think they are all excellent locos, not neccessarily 100% accurate, but they run well and can pull what ever you can afford to put behind them!!
Hope you enjoy your 33,
Rich