So many pretty typewriters! I'm gonna love it here!
And nice Olympia Traveller DeLuxe in green. My first working typewriter was a white Olympia Traveller DeLuxe. It writes great, but sometimes the ribbon-holder don't pop back down after a keystroke.

Once cleaning and lubrication are eliminated, the next most likely cause is a bent ribbon vibrator dragging on something - often the centre guide.  They can be awkward to bend back to the correct shape, even with a pair of flat nose pliers !

I just found this forum, while looking for information about the Groma Kolibri I just got--I was hoping for some sort of a schematic diagram to find out how vigorously I can clean it. It's in perfect working condition however, except for matted detritus from years past, including nicotine stains. It appears to be one of the old model ones--the drawbar drum is very small and on the left. . Its serial number (i.e. the only number I can find anywhere in or on the machine) is right under the spacebar. But the number isn't in the database reported by the manufacturer.

It's a ridiculously elegant thing.  It has this nice, crisp typefont. The best part is that it fits in my backpack.

Thank you all for the information.

(p.s. oh, hello, I just got here. When boardhost lets me, I will post pictures.)

I did read about the dunk method--that's only slightly less creepyfying than disassembling the machine and cleaning out the parts one by one. I've decided I'll just start obsessively brushing off the muck as much as I can and maybe I'll develop the cojones to dunk my (allegedly) portable Royal since that looks much more congested.

I'm posting pictures on my next post--boardhost rules require me to post twice first before being allowed to include links. Apparently, it's how I'm supposed to prove I am human.
 

Great photos and a nice looking Kolibri. I wish mine was in such good condition - one day it will be...

I'm definitely going to compare your photos with my machine to see what other changes to its original design were made. One thing that I immediately noticed is that what I thought was the drawband drum on the older models isn't one at all; it's just a pulley for the drum. As you can see, it the second generation model they eliminated that pulley and moved the drum up so that the drawband could connect to the carriage in a straight line. 

I don't have a number stamp on my machine like yours, so it's safe to say that not only did the serial number location get changed, but so did the serial numbers. I'm assuming of course that Groma didn't differentiate in the way it numbered regular Kolibri machines versus the Luxus variants.

I did have had a breaktrough today on the serial number issue. I came across this sales receipt for a Luxus which proves two things: 1. That the number by the left ribbon spool is the serial number; and 2. My machine was made after 1962. This would also mean that your machine predates 1962. It's not a big revelation, but it helps to build the history of Groma serial numbers.