Home improvement

Paint scraper? If the door jams and frames have the curved mouldings then that could be a real pain in the arse. May have to just start fresh. Sanding alone could just take forever.

I would use a random orbital sander with 220 grit sanding pads (maybe 150 to start if the old repairs are really bad and then 220). Do anything along any profile that the sander can't touch by hand with sheets.

Get the bad spots nice and flat or even negative space.

Neatly skim with something like Ready Patch.

Sand, prime and paint.

Should be pretty easy if the previous paint job adhered decently and it's not peeling.

Unsure if you have a few spots on base boards and door trim you need to repair or if you have a number of entire base boards and door trim pieces you need to repair.

If the latter, it may be easier to just remove and replace.
If its just a few spots here and there you need to sand and repair, my choice for what I would use for sanding would depend on the molding/trim's shape.

Not only do you have to be concerned with bad patch work, but if the previous owner did his own painting and didn't properly prep the trim for paint, you may be in for far more work than you want to tackle taking that approach.

If he used latex paint over oil based paint and didn't properly prep the old paint, there is a good chance the late will "roll" when you try to sand the existing trim.

I've painted way more than my share of trim over the years and what I find works best for me is a rubber sanding block with appropriate grades of paper to do the job for the flat surfaces and simply fold small portions of sandpaper in 3 and then roll it to fit in any curved places to sand them. When done sanding, make sure to clean the surfaces of any dust before applying new paint.