They had not changed ministry in many years. Our theology is solidly Lutheran, but our goal is effective Christian ministry to all. This requires us to ground it all in prayer, and in God's word and Spirit. I do not think it matters whether you are starting a call or you have been there a while. Bring change slowly, gradually .
Most people can handle change in small doses.
I changed worship to a blend of contemporary and traditional. But I did not do it all at once. I did it incrementally, first dropping some of the more formal parts of the Liturgy and using only familiar hymns. Then after a few months we introduced a few contemporary songs and a contemporary confession. Incremental change allowed people time to adapt, to become comfortable.