Hi Andre, both bearing races should not move this means your crankcases are worn out. I would assume this is either TS 125 or ETZ 125 but as you mentioned TS250/1 this is very uncommon.
Best option to tackle it is to replace both cases for a known good pair, alternatively you can fit a new bearing using a bearing fitting compound like Locktite.
Third option, expensive and not really worth doing is to sleeve this bearing journal and have it line bored.
