All I can say is 'wow', well done!

Just wondering, were you aware that is the default setting and that behaviour can be turned off in the 'Memory' options (along with some of the other settings?)
If you had unticked that memory option and it still did it then it would have been a fault, but otherwise is was behaving itself according to your camera settings! If you weren't aware of those memory options it's worth getting acquainted for exposure compensation and drive mode settings etc. too.
I'd hate to think others may pick up on that criticism when there isn't an actual issue to criticize! Maybe the defaults in the ii version are different, or if it is something you mentioned and the technician turned that option off for you.
I can certainly turn my K-1 off and back on and the ISO setting stays the same.

That's very true, but without the people who post here there is no PU. John's said there are no site sponsors so if the board has been misused somehow it needs investigating by its owners. Surely it doesn't hurt to make them aware?
Advertising should be labelled as such, not by crafty hyperlinks.

Thanks John. That South American river also shows as a hyperlink in your post above made at 22.31. In fact it happens every time that retailer is named on PU unless to poster has tweaked the spelling to stop it happening. I've always presumed it was a site sponsor as the American Forum also has similar hyperlinks for some retailers (wonder if theirs are intended?) If it isn't intended on PU has someone craftily added it in as a site feature for their own benefit perhaps? Let the conspiracy theories begin!
Anyhow let's let Haris and Kim get back on topic and the site people investigate that one.

I would think a bit less commercial than SRS listing their lens reductions in the forum or highlighting every instance of Amazon in red in PU with an automatic hyperlink? (I didn't put that one in myself just now.) And we'd certainly be upset if SRS stopped doing what they do. As David says, we surely understand any potential risks and if the lens is otherwise dud is it taking a risk at all?

Hi, back again!! Knew you would.
Does this help?
https://www.youtube.com/watch?v=IrjwRUi3jfQ
If you don't mind a slight bit of vignetting the APSC DA f/2.4 version might be worth a try. While there is some vignetting at f/2.4 it can be corrected in PP and above that it's fine. A truly very light and inexpensive option which I believe to be optically similar to the FA version. It can always be moved on if you don't like it after all.
Another option is the manual focus A f/2.0 (or even M) version which have 7 elements in 7 groups as opposed the DA & FA's 6 elements in 5 groups. Some seem to prefer those.
As you say, the 31mm is better.
Also look up http://stans-photography.info/ - 'best 35mm lens' section in 'Short prime lenses.'
This might be useful too: http://www.takinami.com/yoshihiko/photo/lens_test/pentax_35.html
As to the 35mm f/2.0, yes a fine lens closely matched by the original K SMC PENTAX 35mm f/3.5.

I'd be careful using fungus infected lenses. You wouldn't want the spores jumping ship to wreck another lens.
Someone on the USA forum has described how to deal with an A 50mm F1.7 lens here. I'd presume the process would be comparable for your 120. I gather the 120 has 9 elements in 7 groups (with floating elements.)
Maybe Kim may offer further guidance. At least it isn't an FA one. Are you used to dealing with lens disassembly? In any event good luck if you attempt it.

Take it or send it back?
I've investigated having fungus infected lenses cleaned professionally but was told there is no guarantee that the fungus won't come back.
One thing puzzles me, to my knowledge the only Pentax 645 macro lenses are:
HD PENTAX-D FA 645 Macro 90 mm F2.8 ED AW SR (current)
smc PENTAX-A 645 Macro 120 mm F4.0
smc PENTAX-FA 645 Macro 120 mm F4.0 (current)
But no 100mm ones!
If it is what you say, 100mm, it might be a very rare prototype or something in which case it would almost certainly be worth restoration.
As to help with disassembly, difficult with an unrecognised lens!
Are you sure it isn't this one: https://www.pentaxforums.com/lensreviews/SMC-Pentax-A-100mm-F4-Macro-Lens.html ? But that isn't a 645 lens.

Kim, see you've put it on fleabay. Why not return it for a refund?
Under the 'Consumer Contracts Regulations' when you buy goods online you have additional rights to return them because what you receive isn't always quite what you’d expected.
Under those regulations, you are allowed to return an item if you simply change your mind.
https://www.which.co.uk/consumer-rights/advice/i-want-to-return-something-bought...#the-consumer-contracts-regulations

Mentioned in JR's review at ePhotozine https://www.ephotozine.com/article/hd-pentax-d-fa-15-30mm-f2-8-ed-sdm-wr-review-... .... fourth paragraph.

Surely its not really a problem given it's a very wide angle with AF ?

[quote="JR"]The number of times I would want to manually focus this lens are few and far between, so it may no longer be an issue at all.[/quote]