Hello, and welcome to the list!

        One way to develop a solid multiple tonguing technique is to practice on the alternate syllables: the *K* as it were, rather than the *T*....

        It can help to think of aspirating(hissing air out) as you pronounce the consonant *QUEHEW* (*Q*), much like a small child playing cops and robbers....

        Work on playing this syllable consistently and cleanly, then practice the multiple set backwards(ie: QT,QT,QT or QTT, QTT, QTT) until _that_ sounds clean, then finally practice the regular *TQ,TQ,TQ or TTQ, TTQ, TTQ* slowly, at first and gradually increasing the speed until you can match the required metronome marking on your solo piece...

        It's important to remember that the finest multiple tonguing should sound like very fast single tonguing for the best possible effect...

        Feel free to write back privately for more details...
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Take Care!
Jeannie