I have the same problem. So far nothing has worked for me. However, I have heard that it helps some to either hold out the beginning sound or beginning consonant with stress on the vowel not consonant till the block releases. For me it usually does not release but for others they say it eventually does then gets shorter each time. Also some have said to use 'bumpy speech' to get out block like if you can only make say the S sound in star then try s-s-s-s-star instead of holding it.