(Reuters) -Russian gas flows to Europe remain stable, but Moscow is starting to face problems in selling its crude oil and oil products as Western sanctions over Russia’s invasion of Ukraine and voluntary actions by buyers start to bite. JP Morgan estimated around 70% of Russian seaborne oil was struggling to find buyers, despite record discounts offered for Russian benchmark Urals. The United States imposed a wide ban on Russian oil and gas imports on March 8, and Britain said it would phase out imports of Russian oil by the end of 2022. The European Union, which relies on Russia for 40% of g…