HS Tarm cracked loading door

Hi there folks,
This is my first post but I have been lurking around enough to know that there is a vast amount of collective knowledge/experience on this site. I am going into my second winter with a '70s era HS Tarm OT boiler. I am new to woodstoves/boilers and homeownership in general so the first winter burning wood in the multifuel boiler with no storage was quite a learning experience. In my ignorance, I would load up the firebox and let it idle all night or all day while I was at work. Obviously this created lots of creasote and junk so I did some research and found it was more efficient to burn shorter hot fires. After burning two smallish fires this year, I found two vertical cracks on the loading door. Now, I am not 100% sure that these have formed recently or if I just never noticed them but I am concerned all the same. So I guess I have a few questions.

1. Is it fine to use as is? (I don't think so)
2. Can the cracks be welded? (I hope so)
3. Does the door need to be replaced?
4. If the door needs to be replaced, where would I find parts for this model? I haven't had much luck finding replacement parts for these online

Thanks for any help with this,
-K

Thanks for the input guys. I got it welded up over the weekend and I am going to keep an eye on it. I'm hoping that holds until I can find a new door.

Yea, I don't really have any expectation of them replacing a part on a 30+ year old boiler. I'm not even sure if they still import them at all.