GT Motorcycles are based in California and offer all sorts of Guzzi goodies.

Website: https://gtmotocycles.com/

At last, a British made stainless steel bevel/gear box breather unit is now available for Moto Guzzis. Manufactured by Chris Shaw Engineering, they're available online @ £18.95.

Website: https://www.shawstainless.co.uk/product.php/7049241/

In alphabetical order, a list of companies that offer parts and/or service facilities to UK based Moto Guzzi owners and enthusiasts.

Chris Shaw Engineering - Online Special Stainless Parts.
Tel: 01790 755 515
Website: https://www.shawstainless.co.uk 

Fowlers Parts – Online Parts.
2-12 Bath Road
Bristol
BS4 3DR
Tel: 0117 977 0466
Website: https://www.fowlersparts.co.uk/browser/manufacturer/moto-guzzi 

Gutsibits Moto Guzzi Spares – Online Parts.
Unit 30 Uppermills
Canalside
Slaithwaite
Huddersfield
HD7 5HA
Tel: 01484 841 395
Website: http://www.gutsibits.co.uk/pr/Home/index.php 

Moto Corsa – Service & Online Parts.
Unit 6 Souths Farm Yard
Noade Street
Ashmore
Salisbury
SP5 5AA
Tel: 01747 811196 (Service: Option 2 or Parts: Option 3)
Website: https://www.parts-motoguzzi.com/ 

Robinsons - Service & Parts.
Broad Oak Road
Canterbury
Kent
CT2 7QG
Telephone
Sales 01227 378430
Parts 01227 454366
Service 01227 378460
Website: https://www.robinsonsfoundry.co.uk/moto_guzzi/new-moto_guzzi/moto_guzzi-home.htm 
Through the Moto Guzzi Club GB, Robinsons offer a 12.5% discount off Moto Guzzi parts, clothing, and accessories.
Mention the code ‘GAM1’ on the phone or in email or use the same code when ordering online at checkout.

Stein-Dinse GmbH - Online Parts.
Waller See 11
Schwülper 38179
Germany
Tel: +49 531 123 3000
Website: https://www.stein-dinse.biz/Moto-Guzzi:::1.html?language=en 

Teasdale Motorcycles - Service & Parts
80 Long Street
Thirsk
North Yorkshire
YO7 1AU
Tel: 01845 523310
Website: https://www.teasdale-motorcycles.co.uk 

Teo Lamers – Service & Online Parts.
Lagelandseweg 66
6545 CG Nijmegen
Netherlands
Tel: +31 24 371 1111
Website: http://www.tlm.nl/en/