I bought some replacement cutters and holders for phlilips at890. the holders in my shaver hve two small lugs on each one,the replacement ones dont have these. wil this effect the shave

Most likely, the noise is cause by a damaged blade or comb. The best thing to do is to replace them. You will find the correct replacements for model AT890 at shaveroutlet.com
Norelco Philips HQ8 Spectra Sensotec Precision Replacement Heads

It would appear that the gear is broken or the spring is missing. The tiny part is not available for replacement. The least expensive remedy for this would be to purchase the replacement below for only $9.99 at shaveroutlet.com
Philips Norelco AT752 Shaver Replacement Lower Unit

I am having problems filling in a guarantee form for my AT890 wet and dry shaver

You will try register your AT890 shaver at

https://prod-registration.com/en-us/Norelco/RegisterProduct

Braun makes two distinctly different models, both with called seroes 3-340. You will need the type number as written on the shaver to properly identify the correct foil and cutter for his shaver. Both types are available at shaveroutlet.com. See the two links below. You will need to use the type number of his shaver to select the correct one of these two

http://shaveroutlet.com/shaver-replacement-parts/braun-7000-series-syncro-foil-and-cutter-p-141.html

http://shaveroutlet.com/shaver-replacement-parts/braun-series-3-shaver-foil-and-cutter-head-cassette-32s32b-p-835.html

Based on your description, it seems that the head holder is broken. You will find this part for HQ8894 at shaveroutlet.com. See link below

http://shaveroutlet.com/shaver-replacement-parts/norelco-philips-spectra-sensotec-head-frame-with-hinge-p-329.html

you will find an instructional video at shaveroutlet.com. See link below

http://www.shaveroutlet.com/philips_norelco_heads_replacement

remington SP69 replacement screen foil and cutter blades for electric shaver remington ms2 390 heads replacement parts.

You need a new hed holder. You will find this item at shaveroutlet.com. See link below

http://shaveroutlet.com/remington-head-assembly-without-cutters-for-select-models-p-808.html