Repair advice Sigma Super-wide II 24/2.8 AF

[gmargo]

I recently bought a used Sigma Super-wide II 24/2.8 AF K-mount lens. It was advertised as "excellent" but the feel of the focus movement seemed rough to me. I chose to have it repaired since overall the lens looked good and the few shots I have taken with it showed no obvious problems. I sent it to Sigma for service, but they returned it because they no longer have parts. I tried CRIS hoping they could fix it. They too returned it for lack of parts, but did tell me that the rear seal is missing. Now that I know what to look for the missing seal is obvious. I am no expert but I assume that the lens will deteriorate as dirt gets in where the seal is missing. My guess is that it already needs a cleaning since it has probably been like this for a while.
My post here is to ask if anyone has any suggestion of a repair shop that may have access to old Sigma parts and be able to cobble together a solution. It is obviously not a very valuable lens but I'd rather fix it than toss it, I would not sell it on knowing what I know now, and if it can be fixed it will fill in a gap in the Pentax prime lineup. Thanks for any suggestions.
Geof

 

[Fixcinater]

Does this image show the seal that is missing on your lens? (Not my image)

If you can't find a solution, I have another 28mm for K-mount that you can have for price of shipping.

 

[AgX]

http://kameraspezi.de/werkstatt/sigma.html

 

[gmargo]

Fixcinator: Your photograph does show the rear of the lens mount without any gap. I photographed my lens and you see what is missing:

I will PM you about the 28mm you have; thank you.

AgX: Thanks for the link. I checked out the site and the models of Sigma lenses they repair are more recent than mine. I will email them anyway just in case.

Geof

 

[AgX]

The strange thing is that amongst all german repair shops I checked they were the only one to explicitely state that they do Sigma-repairs (though some shops stated that they do all brands).

 

[gmargo]

AgX, thanks again; I have emailed them with some photographs and I look forward to their reply.

I have since looked at a number of images of the lens online since Fixcinator posted the image above; I realize I cannot see the difference from my lens and I realize I do not really know what I am looking for. I was told by CRIS that the rear seal was missing. What got this going for me is that the focus mechanism is rough and there seems to be something loose inside the lens.

 

[gmargo]

AgX, just to follow up, Kamera Spezialwerkstatt got back to me but cannot help, no more parts.
Geof

 

[benjiboy]

If this lens was mine I would put it in the bin, and buy something else, life's too short for the aggravation it causes.

 

[gmargo]

I am coming around to that viewpoint!
Geof